diff --git a/packages/collections/package.json b/packages/collections/package.json
new file mode 100644
index 000000000..d66baf9be
--- /dev/null
+++ b/packages/collections/package.json
@@ -0,0 +1,21 @@
+{
+  "name": "@nocobase/collections",
+  "version": "0.4.0-alpha.7",
+  "description": "",
+  "main": "./lib/index.js",
+  "types": "./lib/index.d.ts",
+  "license": "MIT",
+  "scripts": {},
+  "dependencies": {
+    "bcrypt": "^5.0.0",
+    "deepmerge": "^4.2.2",
+    "glob": "^7.1.6",
+    "sequelize": "^6.3.3"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/nocobase/nocobase.git",
+    "directory": "packages/database"
+  },
+  "gitHead": "f0b335ac30f29f25c95d7d137655fa64d8d67f1e"
+}
diff --git a/packages/collections/src/__tests__/index.ts b/packages/collections/src/__tests__/index.ts
new file mode 100644
index 000000000..bc70cdd80
--- /dev/null
+++ b/packages/collections/src/__tests__/index.ts
@@ -0,0 +1,40 @@
+import merge from 'deepmerge';
+import { Database, DatabaseOptions } from '../database';
+
+export function generatePrefixByPath() {
+  const { id } = require.main;
+  const key = id
+    .replace(`${process.env.PWD}/packages`, '')
+    .replace(/src\/__tests__/g, '')
+    .replace('.test.ts', '')
+    .replace(/[^\w]/g, '_')
+    .replace(/_+/g, '_');
+  return key
+}
+
+export function getConfig(config = {}, options?: any): DatabaseOptions {
+  return merge({
+    username: process.env.DB_USER,
+    password: process.env.DB_PASSWORD,
+    database: process.env.DB_DATABASE,
+    host: process.env.DB_HOST,
+    port: process.env.DB_PORT,
+    dialect: process.env.DB_DIALECT,
+    logging: process.env.DB_LOG_SQL === 'on',
+    sync: {
+      force: true,
+      alter: {
+        drop: true,
+      },
+    },
+    hooks: {
+      beforeDefine(model, options) {
+        options.tableName = `${generatePrefixByPath()}_${options.tableName || options.modelName || options.name.plural}`;
+      },
+    },
+  }, config || {}, options) as any;
+};
+
+export function mockDatabase(options?: DatabaseOptions): Database {
+  return new Database(getConfig(options));
+}
diff --git a/packages/collections/src/__tests__/schema-fields/belongs-to-field.test.ts b/packages/collections/src/__tests__/schema-fields/belongs-to-field.test.ts
new file mode 100644
index 000000000..e43a6ba58
--- /dev/null
+++ b/packages/collections/src/__tests__/schema-fields/belongs-to-field.test.ts
@@ -0,0 +1,151 @@
+import { Database } from '../../database';
+import { mockDatabase } from '../';
+
+describe('belongs to field', () => {
+  let db: Database;
+
+  beforeEach(() => {
+    db = mockDatabase();
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('association undefined', async () => {
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [{ type: 'belongsTo', name: 'post' }],
+    });
+    expect(Comment.model.associations['post']).toBeUndefined();
+  });
+
+  it('association defined', async () => {
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [
+        { type: 'string', name: 'content' },
+        { type: 'belongsTo', name: 'post' },
+      ],
+    });
+    expect(Comment.model.associations.post).toBeUndefined();
+    const Post = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'title' },
+      ],
+    });
+    const association = Comment.model.associations.post;
+    expect(Comment.model.associations.post).toBeDefined();
+    expect(association.foreignKey).toBe('postId');
+    // @ts-ignore
+    expect(association.targetKey).toBe('id');
+    expect(Comment.model.rawAttributes.postId).toBeDefined();
+    await db.sync();
+    const comment = await Comment.model.create<any>();
+    await comment.createPost({
+      title: 'title222',
+    });
+    const post1 = await comment.getPost();
+    expect(post1.toJSON()).toMatchObject({
+      title: 'title222',
+    });
+    const post = await Post.model.create<any>({
+      title: 'title111'
+    });
+    await comment.setPost(post);
+    const post2 = await comment.getPost();
+    expect(post2.toJSON()).toMatchObject({
+      title: 'title111',
+    });
+  });
+
+  it('custom targetKey and foreignKey', async () => {
+    const Post = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'key', unique: true },
+      ],
+    });
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [
+        {
+          type: 'belongsTo',
+          name: 'post',
+          targetKey: 'key',
+          foreignKey: 'postKey',
+        },
+      ],
+    });
+    const association = Comment.model.associations.post;
+    expect(association).toBeDefined();
+    expect(association.foreignKey).toBe('postKey');
+    // @ts-ignore
+    expect(association.targetKey).toBe('key');
+    expect(Comment.model.rawAttributes['postKey']).toBeDefined();
+  });
+
+  it('custom name and target', async () => {
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [
+        { type: 'string', name: 'content' },
+        {
+          type: 'belongsTo',
+          name: 'article',
+          target: 'posts',
+          targetKey: 'key',
+          foreignKey: 'postKey',
+        },
+      ],
+    });
+    expect(Comment.model.associations.article).toBeUndefined();
+    const Post = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'key', unique: true },
+      ],
+    });
+    const association = Comment.model.associations.article;
+    expect(Comment.model.associations.article).toBeDefined();
+    expect(association.foreignKey).toBe('postKey');
+    // @ts-ignore
+    expect(association.targetKey).toBe('key');
+    expect(Comment.model.rawAttributes.postKey).toBeDefined();
+    await db.sync();
+    const comment = await Comment.model.create<any>();
+    await comment.createArticle({
+      key: 'title222',
+    });
+    const post1 = await comment.getArticle();
+    expect(post1.toJSON()).toMatchObject({
+      key: 'title222',
+    });
+    const post = await Post.model.create<any>({
+      key: 'title111'
+    });
+    await comment.setArticle(post);
+    const post2 = await comment.getArticle();
+    expect(post2.toJSON()).toMatchObject({
+      key: 'title111',
+    });
+  });
+
+  it('schema delete', async () => {
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [{ type: 'belongsTo', name: 'post' }],
+    });
+    const Post = db.collection({
+      name: 'posts',
+      schema: [{ type: 'hasMany', name: 'comments' }],
+    });
+    // await db.sync();
+    Comment.schema.delete('post');
+    expect(Comment.model.associations.post).toBeUndefined();
+    expect(Comment.model.rawAttributes.postId).toBeDefined();
+    Post.schema.delete('comments');
+    expect(Comment.model.rawAttributes.postId).toBeUndefined();
+  });
+});
diff --git a/packages/collections/src/__tests__/schema-fields/belongs-to-many-field.test.ts b/packages/collections/src/__tests__/schema-fields/belongs-to-many-field.test.ts
new file mode 100644
index 000000000..1e41015b0
--- /dev/null
+++ b/packages/collections/src/__tests__/schema-fields/belongs-to-many-field.test.ts
@@ -0,0 +1,42 @@
+import { Database } from '../../database';
+import { mockDatabase } from '../';
+
+describe('belongs to many field', () => {
+  let db: Database;
+
+  beforeEach(() => {
+    db = mockDatabase();
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('association undefined', async () => {
+    const Post = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'name' },
+        { type: 'belongsToMany', name: 'tags' },
+      ],
+    });
+    expect(Post.model.associations.tags).toBeUndefined();
+    expect(db.getCollection('posts_tags')).toBeUndefined();
+    const Tag = db.collection({
+      name: 'tags',
+      schema: [
+        { type: 'string', name: 'name' },
+      ],
+    });
+    expect(Post.model.associations.tags).toBeDefined();
+    const Through = db.getCollection('posts_tags');
+    expect(Through).toBeDefined();
+    expect(Through.model.rawAttributes['postId']).toBeDefined();
+    expect(Through.model.rawAttributes['tagId']).toBeDefined();
+    const PostTag = db.collection({
+      name: 'posts_tags',
+    });
+    expect(PostTag.model.rawAttributes['postId']).toBeDefined();
+    expect(PostTag.model.rawAttributes['tagId']).toBeDefined();
+  });
+});
diff --git a/packages/collections/src/__tests__/schema-fields/has-many-field.test.ts b/packages/collections/src/__tests__/schema-fields/has-many-field.test.ts
new file mode 100644
index 000000000..026043983
--- /dev/null
+++ b/packages/collections/src/__tests__/schema-fields/has-many-field.test.ts
@@ -0,0 +1,129 @@
+import { Database } from '../../database';
+import { mockDatabase } from '../';
+
+describe('has many field', () => {
+  let db: Database;
+
+  beforeEach(() => {
+    db = mockDatabase();
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('association undefined', async () => {
+    const collection = db.collection({
+      name: 'posts',
+      schema: [{ type: 'hasMany', name: 'comments' }],
+    });
+    await db.sync();
+    expect(collection.model.associations['comments']).toBeUndefined();
+  });
+
+  it('association defined', async () => {
+    const { model } = db.collection({
+      name: 'posts',
+      schema: [{ type: 'hasMany', name: 'comments' }],
+    });
+    expect(model.associations['comments']).toBeUndefined();
+    const comments = db.collection({
+      name: 'comments',
+      schema: [{ type: 'string', name: 'content' }],
+    });
+    const association = model.associations.comments;
+    expect(association).toBeDefined();
+    expect(association.foreignKey).toBe('postId');
+    // @ts-ignore
+    expect(association.sourceKey).toBe('id');
+    expect(comments.model.rawAttributes['postId']).toBeDefined();
+    await db.sync();
+    const post = await model.create<any>();
+    await post.createComment({
+      content: 'content111',
+    });
+    const postComments = await post.getComments();
+    expect(postComments.map((comment) => comment.content)).toEqual([
+      'content111',
+    ]);
+  });
+
+  it('custom sourceKey and foreignKey', async () => {
+    const collection = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'key', unique: true },
+        {
+          type: 'hasMany',
+          name: 'comments',
+          sourceKey: 'key',
+          foreignKey: 'postKey',
+        },
+      ],
+    });
+    const comments = db.collection({
+      name: 'comments',
+      schema: [],
+    });
+    const association = collection.model.associations.comments;
+    expect(association).toBeDefined();
+    expect(association.foreignKey).toBe('postKey');
+    // @ts-ignore
+    expect(association.sourceKey).toBe('key');
+    expect(comments.model.rawAttributes['postKey']).toBeDefined();
+    await db.sync();
+  });
+
+  it('custom name and target', async () => {
+    const collection = db.collection({
+      name: 'posts',
+      schema: [
+        { type: 'string', name: 'key', unique: true },
+        {
+          type: 'hasMany',
+          name: 'reviews',
+          target: 'comments',
+          sourceKey: 'key',
+          foreignKey: 'postKey',
+        },
+      ],
+    });
+    db.collection({
+      name: 'comments',
+      schema: [{ type: 'string', name: 'content' }],
+    });
+    const association = collection.model.associations.reviews;
+    expect(association).toBeDefined();
+    expect(association.foreignKey).toBe('postKey');
+    // @ts-ignore
+    expect(association.sourceKey).toBe('key');
+    await db.sync();
+    const post = await collection.model.create<any>({
+      key: 'key1',
+    });
+    await post.createReview({
+      content: 'content111',
+    });
+    const postComments = await post.getReviews();
+    expect(postComments.map((comment) => comment.content)).toEqual([
+      'content111',
+    ]);
+  });
+
+  it('schema delete', async () => {
+    const Post = db.collection({
+      name: 'posts',
+      schema: [{ type: 'hasMany', name: 'comments' }],
+    });
+    const Comment = db.collection({
+      name: 'comments',
+      schema: [{ type: 'belongsTo', name: 'post' }],
+    });
+    await db.sync();
+    Post.schema.delete('comments');
+    expect(Post.model.associations.comments).toBeUndefined();
+    expect(Comment.model.rawAttributes.postId).toBeDefined();
+    Comment.schema.delete('post');
+    expect(Comment.model.rawAttributes.postId).toBeUndefined();
+  });
+});
diff --git a/packages/collections/src/__tests__/schema-fields/string-field.test.ts b/packages/collections/src/__tests__/schema-fields/string-field.test.ts
new file mode 100644
index 000000000..acd389817
--- /dev/null
+++ b/packages/collections/src/__tests__/schema-fields/string-field.test.ts
@@ -0,0 +1,79 @@
+import { Database } from '../../database';
+import { mockDatabase } from '../';
+
+describe('string field', () => {
+  let db: Database;
+
+  beforeEach(() => {
+    db = mockDatabase();
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('define', async () => {
+    const Test = db.collection({
+      name: 'tests',
+      schema: [
+        { type: 'string', name: 'name' },
+      ],
+    });
+    await db.sync();
+    expect(Test.model.rawAttributes['name']).toBeDefined();
+    const model = await Test.model.create({
+      name: 'abc',
+    });
+    expect(model.toJSON()).toMatchObject({
+      name: 'abc',
+    });
+  });
+
+  it('set', async () => {
+    const Test = db.collection({
+      name: 'tests',
+      schema: [
+        { type: 'string', name: 'name1' },
+      ],
+    });
+    await db.sync();
+    Test.schema.set('name2', { type: 'string' });
+    await db.sync();
+    expect(Test.model.rawAttributes['name1']).toBeDefined();
+    expect(Test.model.rawAttributes['name2']).toBeDefined();
+    const model = await Test.model.create({
+      name1: 'a1',
+      name2: 'a2',
+    });
+    expect(model.toJSON()).toMatchObject({
+      name1: 'a1',
+      name2: 'a2',
+    });
+  });
+
+  it('model hook', async () => {
+    const collection = db.collection({
+      name: 'tests',
+      schema: [
+        { type: 'string', name: 'name' },
+      ],
+    });
+    await db.sync();
+    collection.model.beforeCreate((model) => {
+      const changed = model.changed();
+      for (const name of changed || []) {
+        model.set(name, `${model.get(name)}111`);
+      }
+    });
+    collection.schema.set('name2', { type: 'string' });
+    await db.sync();
+    const model = await collection.model.create({
+      name: 'n1',
+      name2: 'n2',
+    });
+    expect(model.toJSON()).toMatchObject({
+      name: 'n1111',
+      name2: 'n2111',
+    });
+  });
+});
diff --git a/packages/collections/src/collection.ts b/packages/collections/src/collection.ts
new file mode 100644
index 000000000..0fd5d8576
--- /dev/null
+++ b/packages/collections/src/collection.ts
@@ -0,0 +1,59 @@
+import { ModelCtor, Model } from 'sequelize';
+import { Database } from './database';
+import { Schema } from './schema';
+import { RelationField } from './schema-fields';
+import _ from 'lodash';
+
+export interface CollectionOptions {
+  schema?: any;
+  [key: string]: any;
+}
+
+export interface CollectionContext {
+  database: Database;
+}
+
+export class Collection {
+  schema: Schema;
+  model: ModelCtor<Model>;
+  options: CollectionOptions;
+  context: CollectionContext;
+
+  get name() {
+    return this.options.name;
+  }
+
+  constructor(options: CollectionOptions, context: CollectionContext) {
+    this.options = options;
+    this.context = context;
+    const { name, tableName } = options;
+    this.model = class extends Model<any, any> {};
+    const attributes = {};
+    this.model.init(attributes, {
+      ..._.omit(options, ['name', 'schema']),
+      sequelize: context.database.sequelize,
+      modelName: name,
+      tableName: tableName || name,
+    });
+    this.schema = new Schema(options.schema, {
+      ...context,
+      collection: this,
+    });
+    this.schema2model();
+    this.context.database.emit('collection.init', this);
+  }
+
+  schema2model() {
+    this.schema.forEach((field) => {
+      field.bind();
+    });
+    this.schema.on('setted', (field) => {
+      // console.log('setted', field);
+      field.bind();
+    });
+    this.schema.on('deleted', (field) => field.unbind());
+    this.schema.on('merged', (field) => {
+      //
+    });
+  }
+}
diff --git a/packages/collections/src/database.ts b/packages/collections/src/database.ts
new file mode 100644
index 000000000..0d88b36fe
--- /dev/null
+++ b/packages/collections/src/database.ts
@@ -0,0 +1,103 @@
+import { Sequelize, ModelCtor, Model, Options, SyncOptions } from 'sequelize';
+import { EventEmitter } from 'events';
+import { Collection, CollectionOptions } from './collection';
+import {
+  RelationField,
+  StringField,
+  HasManyField,
+  BelongsToField,
+  BelongsToManyField,
+  JsonField,
+  JsonbField,
+} from './schema-fields';
+
+export interface PendingOptions {
+  field: RelationField;
+  model: ModelCtor<Model>;
+}
+
+export type DatabaseOptions = Options | Sequelize;
+
+export class Database extends EventEmitter {
+  sequelize: Sequelize;
+  schemaTypes = new Map();
+  collections: Map<string, Collection>;
+  pendingFields = new Map<string, RelationField[]>();
+
+  constructor(options: DatabaseOptions) {
+    super();
+    if (options instanceof Sequelize) {
+      this.sequelize = options;
+    } else {
+      this.sequelize = new Sequelize(options);
+    }
+    this.collections = new Map();
+    this.on('collection.init', (collection) => {
+      const items = this.pendingFields.get(collection.name);
+      for (const field of items || []) {
+        field.bind();
+      }
+    });
+    this.registerSchemaTypes({
+      string: StringField,
+      json: JsonField,
+      jsonb: JsonbField,
+      hasMany: HasManyField,
+      belongsTo: BelongsToField,
+      belongsToMany: BelongsToManyField,
+    });
+  }
+
+  collection(options: CollectionOptions) {
+    let collection = this.collections.get(options.name);
+    if (collection) {
+      collection.schema.set(options.schema);
+    } else {
+      collection = new Collection(options, { database: this });
+    }
+    this.collections.set(collection.name, collection);
+    return collection;
+  }
+
+  getCollection(name: string) {
+    return this.collections.get(name);
+  }
+
+  addPendingField(field: RelationField) {
+    const associating = this.pendingFields;
+    const items = this.pendingFields.get(field.target) || [];
+    items.push(field);
+    associating.set(field.target, items);
+  }
+
+  removePendingField(field: RelationField) {
+    const items = this.pendingFields.get(field.target) || [];
+    const index = items.findIndex(
+      (item) => item && item.name === field.name,
+    );
+    if (index !== -1) {
+      delete items[index];
+      this.pendingFields.set(field.target, items);
+    }
+  }
+
+  registerSchemaTypes(schemaTypes: any) {
+    for (const [type, schemaType] of Object.entries(schemaTypes)) {
+      this.schemaTypes.set(type, schemaType);
+    }
+  }
+
+  buildSchemaField(options, context) {
+    const { type } = options;
+    const Field = this.schemaTypes.get(type);
+    return new Field(options, context);
+  }
+
+  async sync(options?: SyncOptions) {
+    return this.sequelize.sync(options);
+  }
+
+  async close() {
+    return this.sequelize.close();
+  }
+}
diff --git a/packages/collections/src/index.ts b/packages/collections/src/index.ts
new file mode 100644
index 000000000..e69de29bb
diff --git a/packages/collections/src/schema-fields/belongs-to-field.ts b/packages/collections/src/schema-fields/belongs-to-field.ts
new file mode 100644
index 000000000..297a1a537
--- /dev/null
+++ b/packages/collections/src/schema-fields/belongs-to-field.ts
@@ -0,0 +1,53 @@
+import { omit } from 'lodash';
+import { Sequelize, ModelCtor, Model, DataTypes, Utils } from 'sequelize';
+import { RelationField } from './relation-field';
+
+export class BelongsToField extends RelationField {
+  get target() {
+    const { target, name } = this.options;
+    return target || Utils.pluralize(name);
+  }
+
+  bind() {
+    const { database, collection } = this.context;
+    const Target = this.TargetModel;
+    if (!Target) {
+      database.addPendingField(this);
+      return false;
+    }
+    const association = collection.model.belongsTo(Target, {
+      as: this.name,
+      ...omit(this.options, ['name', 'type', 'target']),
+    });
+    // 建立关系之后从 pending 列表中删除
+    database.removePendingField(this);
+    if (!this.options.foreignKey) {
+      this.options.foreignKey = association.foreignKey;
+    }
+    if (!this.options.sourceKey) {
+      // @ts-ignore
+      this.options.sourceKey = association.sourceKey;
+    }
+    return true;
+  }
+
+  unbind() {
+    const { database, collection } = this.context;
+    // 如果关系字段还没建立就删除了，也同步删除待建立关联的关系字段
+    database.removePendingField(this);
+    // 如果外键没有显式的创建，关系表也无反向关联字段，删除关系时，外键也删除掉
+    const tcoll = database.collections.get(this.target);
+    const foreignKey = this.options.foreignKey;
+    const field1 = collection.schema.get(foreignKey);
+    const field2 = tcoll.schema.find((field) => {
+      return field.type === 'hasMany' && field.foreignKey === foreignKey;
+    });
+    if (!field1 && !field2) {
+      collection.model.removeAttribute(foreignKey);
+    }
+    // 删掉 model 的关联字段
+    delete collection.model.associations[this.name];
+    // @ts-ignore
+    collection.model.refreshAttributes();
+  }
+}
diff --git a/packages/collections/src/schema-fields/belongs-to-many-field.ts b/packages/collections/src/schema-fields/belongs-to-many-field.ts
new file mode 100644
index 000000000..a5be4cb6c
--- /dev/null
+++ b/packages/collections/src/schema-fields/belongs-to-many-field.ts
@@ -0,0 +1,69 @@
+import { omit } from 'lodash';
+import { Sequelize, ModelCtor, Model, DataTypes, Utils } from 'sequelize';
+import { RelationField } from './relation-field';
+
+export class BelongsToManyField extends RelationField {
+  get target() {
+    const { target, name } = this.options;
+    return target || name;
+  }
+
+  get through() {
+    return (
+      this.options.through ||
+      [this.context.collection.model.name, this.target]
+        .map((name) => name.toLowerCase())
+        .sort()
+        .join('_')
+    );
+  }
+
+  bind() {
+    const { database, collection } = this.context;
+    const Target = this.TargetModel;
+    if (!Target) {
+      database.addPendingField(this);
+      return false;
+    }
+    const through = this.through;
+    let Through =
+      database.getCollection(through) ||
+      database.collection({
+        name: through,
+      });
+    const association = collection.model.belongsToMany(Target, {
+      ...omit(this.options, ['name', 'type', 'target']),
+      as: this.name,
+      through: Through.model,
+    });
+    // 建立关系之后从 pending 列表中删除
+    database.removePendingField(this);
+    if (!this.options.foreignKey) {
+      this.options.foreignKey = association.foreignKey;
+    }
+    if (!this.options.sourceKey) {
+      this.options.sourceKey = association.sourceKey;
+    }
+    return true;
+  }
+
+  unbind() {
+    // const { database, collection } = this.context;
+    // // 如果关系字段还没建立就删除了，也同步删除待建立关联的关系字段
+    // database.removePendingField(this);
+    // // 如果外键没有显式的创建，关系表也无反向关联字段，删除关系时，外键也删除掉
+    // const tcoll = database.collections.get(this.target);
+    // const foreignKey = this.options.foreignKey;
+    // const field1 = collection.schema.get(foreignKey);
+    // const field2 = tcoll.schema.find((field) => {
+    //   return field.type === 'hasMany' && field.foreignKey === foreignKey;
+    // });
+    // if (!field1 && !field2) {
+    //   collection.model.removeAttribute(foreignKey);
+    // }
+    // // 删掉 model 的关联字段
+    // delete collection.model.associations[this.name];
+    // // @ts-ignore
+    // collection.model.refreshAttributes();
+  }
+}
diff --git a/packages/collections/src/schema-fields/has-many-field.ts b/packages/collections/src/schema-fields/has-many-field.ts
new file mode 100644
index 000000000..d7807820a
--- /dev/null
+++ b/packages/collections/src/schema-fields/has-many-field.ts
@@ -0,0 +1,119 @@
+import { omit } from 'lodash';
+import {
+  Sequelize,
+  ModelCtor,
+  Model,
+  DataType,
+  AssociationScope,
+  ForeignKeyOptions,
+  HasManyOptions,
+} from 'sequelize';
+import { RelationField } from './relation-field';
+
+export interface HasManyFieldOptions extends HasManyOptions {
+  /**
+   * The name of the field to use as the key for the association in the source table. Defaults to the primary
+   * key of the source table
+   */
+  sourceKey?: string;
+
+  /**
+   * A string or a data type to represent the identifier in the table
+   */
+  keyType?: DataType;
+
+  scope?: AssociationScope;
+
+  /**
+   * The alias of this model, in singular form. See also the `name` option passed to `sequelize.define`. If
+   * you create multiple associations between the same tables, you should provide an alias to be able to
+   * distinguish between them. If you provide an alias when creating the assocition, you should provide the
+   * same alias when eager loading and when getting associated models. Defaults to the singularized name of
+   * target
+   */
+  as?: string | { singular: string; plural: string };
+
+  /**
+   * The name of the foreign key in the target table or an object representing the type definition for the
+   * foreign column (see `Sequelize.define` for syntax). When using an object, you can add a `name` property
+   * to set the name of the column. Defaults to the name of source + primary key of source
+   */
+  foreignKey?: string | ForeignKeyOptions;
+
+  /**
+   * What happens when delete occurs.
+   *
+   * Cascade if this is a n:m, and set null if it is a 1:m
+   *
+   * @default 'SET NULL' or 'CASCADE'
+   */
+  onDelete?: string;
+
+  /**
+   * What happens when update occurs
+   *
+   * @default 'CASCADE'
+   */
+  onUpdate?: string;
+
+  /**
+   * Should on update and on delete constraints be enabled on the foreign key.
+   */
+  constraints?: boolean;
+  foreignKeyConstraint?: boolean;
+
+  // scope?: AssociationScope;
+
+  /**
+   * If `false` the applicable hooks will not be called.
+   * The default value depends on the context.
+   */
+  hooks?: boolean;
+}
+
+export class HasManyField extends RelationField {
+  bind() {
+    const { database, collection } = this.context;
+    const Target = this.TargetModel;
+    if (!Target) {
+      database.addPendingField(this);
+      return false;
+    }
+    const association = collection.model.hasMany(Target, {
+      as: this.name,
+      ...omit(this.options, ['name', 'type', 'target']),
+    });
+    // 建立关系之后从 pending 列表中删除
+    database.removePendingField(this);
+    if (!this.options.foreignKey) {
+      this.options.foreignKey = association.foreignKey;
+    }
+    if (!this.options.sourceKey) {
+      // @ts-ignore
+      this.options.sourceKey = association.sourceKey;
+    }
+    return true;
+  }
+
+  unbind() {
+    const { database, collection } = this.context;
+    // 如果关系字段还没建立就删除了，也同步删除待建立关联的关系字段
+    database.removePendingField(this);
+    // 如果关系表内没有显式的创建外键字段，删除关系时，外键也删除掉
+    const tcoll = database.collections.get(this.target);
+    const foreignKey = this.options.foreignKey;
+    const field = tcoll.schema.find((field) => {
+      if (field.name === foreignKey) {
+        return true;
+      }
+      return field.type === 'belongsTo' && field.foreignKey === foreignKey;
+    });
+    if (!field) {
+      tcoll.model.removeAttribute(foreignKey);
+    }
+    // 删掉 model 的关联字段
+    delete collection.model.associations[this.name];
+    // @ts-ignore
+    collection.model.refreshAttributes();
+  }
+}
diff --git a/packages/collections/src/schema-fields/has-one-field.ts b/packages/collections/src/schema-fields/has-one-field.ts
new file mode 100644
index 000000000..e69de29bb
diff --git a/packages/collections/src/schema-fields/index.ts b/packages/collections/src/schema-fields/index.ts
new file mode 100644
index 000000000..4246b10a6
--- /dev/null
+++ b/packages/collections/src/schema-fields/index.ts
@@ -0,0 +1,7 @@
+export * from './schema-field';
+export * from './string-field';
+export * from './relation-field'
+export * from './belongs-to-field'
+export * from './belongs-to-many-field';
+export * from './has-many-field';
+export * from './json-field';
diff --git a/packages/collections/src/schema-fields/json-field.ts b/packages/collections/src/schema-fields/json-field.ts
new file mode 100644
index 000000000..568e8d8d2
--- /dev/null
+++ b/packages/collections/src/schema-fields/json-field.ts
@@ -0,0 +1,32 @@
+import { DataTypes } from 'sequelize';
+import { SchemaField } from './schema-field';
+
+export class JsonField extends SchemaField {
+  get dataType() {
+    return DataTypes.JSON;
+  }
+
+  toSequelize() {
+    return {
+      ...this.options,
+      type: this.dataType,
+    };
+  }
+}
+
+export class JsonbField extends SchemaField {
+  get dataType() {
+    const dialect = this.context.database.sequelize.getDialect();
+    if (dialect === 'postgres') {
+      return DataTypes.JSONB;
+    }
+    return DataTypes.JSON;
+  }
+
+  toSequelize() {
+    return {
+      ...this.options,
+      type: this.dataType,
+    };
+  }
+}
diff --git a/packages/collections/src/schema-fields/relation-field.ts b/packages/collections/src/schema-fields/relation-field.ts
new file mode 100644
index 000000000..1efde44cd
--- /dev/null
+++ b/packages/collections/src/schema-fields/relation-field.ts
@@ -0,0 +1,20 @@
+import { SchemaField } from './schema-field';
+
+export abstract class RelationField extends SchemaField {
+  get target() {
+    const { target, name } = this.options;
+    return target || name;
+  }
+
+  get foreignKey() {
+    return this.options.foreignKey;
+  }
+
+  get sourceKey() {
+    return this.options.sourceKey;
+  }
+
+  get TargetModel() {
+    return this.context.database.sequelize.models[this.target];
+  }
+}
diff --git a/packages/collections/src/schema-fields/schema-field.ts b/packages/collections/src/schema-fields/schema-field.ts
new file mode 100644
index 000000000..c872be6de
--- /dev/null
+++ b/packages/collections/src/schema-fields/schema-field.ts
@@ -0,0 +1,65 @@
+import { Sequelize, ModelCtor, Model, DataTypes, Utils } from 'sequelize';
+import { EventEmitter } from 'events';
+import { Collection } from '../collection';
+import { Database } from '../database';
+import { Schema } from '../schema';
+import { RelationField } from './relation-field';
+import _ from 'lodash';
+
+export interface SchemaFieldContext {
+  database: Database;
+  collection: Collection;
+  schema: Schema;
+}
+
+export abstract class SchemaField {
+  options: any;
+  context: SchemaFieldContext;
+  [key: string]: any;
+
+  get name() {
+    return this.options.name;
+  }
+
+  get type() {
+    return this.options.type;
+  }
+
+  get dataType() {
+    return this.options.dataType;
+  }
+
+  constructor(options?: any, context?: SchemaFieldContext) {
+    this.context = context;
+    this.options = options || {};
+    this.init();
+  }
+
+  init() {
+    // code
+  }
+
+  get(name: string) {
+    return this.options[name];
+  }
+
+  merge(obj: any) {
+    Object.assign(this.options, obj);
+  }
+
+  bind() {
+    const { model } = this.context.collection;
+    model.rawAttributes[this.name] = this.toSequelize();
+    // @ts-ignore
+    model.refreshAttributes();
+  }
+
+  unbind() {
+    const { model } = this.context.collection;
+    model.removeAttribute(this.name);
+  }
+
+  toSequelize(): any {
+    return _.omit(this.options, ['name'])
+  }
+}
diff --git a/packages/collections/src/schema-fields/string-field.ts b/packages/collections/src/schema-fields/string-field.ts
new file mode 100644
index 000000000..cc8e06d55
--- /dev/null
+++ b/packages/collections/src/schema-fields/string-field.ts
@@ -0,0 +1,15 @@
+import { DataTypes } from 'sequelize';
+import { SchemaField } from './schema-field';
+
+export class StringField extends SchemaField {
+  get dataType() {
+    return DataTypes.STRING;
+  }
+
+  toSequelize() {
+    return {
+      ...this.options,
+      type: this.dataType,
+    };
+  }
+}
diff --git a/packages/collections/src/schema.ts b/packages/collections/src/schema.ts
new file mode 100644
index 000000000..2c5cf1250
--- /dev/null
+++ b/packages/collections/src/schema.ts
@@ -0,0 +1,80 @@
+import { Sequelize, ModelCtor, Model, DataTypes, Utils } from 'sequelize';
+import { EventEmitter } from 'events';
+import { Database } from './database';
+import { Collection } from './collection';
+import { SchemaField } from './schema-fields';
+
+export interface SchemaContext {
+  database: Database;
+  collection: Collection;
+}
+
+export class Schema extends EventEmitter {
+  fields: Map<string, any>;
+  context: SchemaContext;
+  options: any;
+
+  constructor(options?: any, context?: SchemaContext) {
+    super();
+    this.options = options;
+    this.context = context;
+    this.fields = new Map<string, any>();
+    this.set(options);
+  }
+
+  has(name: string) {
+    return this.fields.has(name);
+  }
+
+  get(name: string) {
+    return this.fields.get(name);
+  }
+
+  set(name: string | object, obj?: any) {
+    if (!name) {
+      return this;
+    }
+    if (typeof name === 'string') {
+      const { database } = this.context;
+      const field = database.buildSchemaField({ name, ...obj }, {
+        ...this.context,
+        schema: this,
+        model: this.context.collection.model,
+      });
+      this.fields.set(name, field);
+      this.emit('setted', field);
+    } else if (Array.isArray(name)) {
+      for (const value of name) {
+        this.set(value.name, value);
+      }
+    } else if (typeof name === 'object') {
+      for (const [key, value] of Object.entries(name)) {
+        console.log({ key, value })
+        this.set(key, value);
+      }
+    }
+    return this;
+  }
+
+  delete(name: string) {
+    const field = this.fields.get(name);
+    const bool = this.fields.delete(name);
+    this.emit('deleted', field);
+    return bool;
+  }
+
+  merge(name: string, obj) {
+    const field = this.get(name);
+    field.merge(obj);
+    this.emit('merged', field);
+    return field;
+  }
+
+  forEach(callback: (field: SchemaField) => void) {
+    return [...this.fields.values()].forEach(callback);
+  }
+
+  find(callback: (field: SchemaField) => boolean) {
+    return [...this.fields.values()].find(callback);
+  }
+}