diff --git a/server/data/Chat.ts b/server/data/Chat.ts
index 4033ed2..e4d13ce 100644
--- a/server/data/Chat.ts
+++ b/server/data/Chat.ts
@@ -8,6 +8,7 @@ import { SQLInputValue } from "node:sqlite"
 import chalk from "chalk"
 import User from "./User.ts"
 import ChatType from "./ChatType.ts"
+import UserChatLinker from "./UserChatLinker.ts"
 
 /**
  * Chat.ts - Wrapper and manager
@@ -55,14 +56,12 @@ export default class Chat {
                     id,
                     title,
                     avatar,
-                    members_list,
                     settings
-                ) VALUES (?, ?, ?, ?, ?, ?);`).run(
+                ) VALUES (?, ?, ?, ?, ?);`).run(
                     type,
                     chatId,
                     null,
                     null,
-                    "[]",
                     "{}"
                 ).lastInsertRowid
             )[0]
@@ -80,19 +79,13 @@ export default class Chat {
     }
 
     getMembersList() {
-        return JSON.parse(this.bean.members_list) as string[]
+        return UserChatLinker.getChatMembers(this.bean.id)
     }
-    addMember(userId: string) {
-        const ls = this.getMembersList()
-        ls.push(userId)
-        this.setMembers(ls)
+    addMembers(userIds: string[]) {
+        userIds.forEach((v) => UserChatLinker.linkUserAndChat(v, this.bean.id))
     }
-    setMembers(members: string[]) {
-        this.setAttr("members_list", JSON.stringify(members))
-    }
-    removeMembers(members: string[]) {
-        const ls = this.getMembersList().filter((v) => !members.includes(v))
-        this.setAttr("members_list", JSON.stringify(ls))
+    removeMembers(userIds: string[]) {
+        userIds.forEach((v) => UserChatLinker.unlinkUserAndChat(v, this.bean.id))
     }
     getAnotherUserForPrivate(userMySelf: User) {
         const user_a_id = this.getMembersList()[0]
diff --git a/server/data/ChatPrivate.ts b/server/data/ChatPrivate.ts
index 28889e5..09d1777 100644
--- a/server/data/ChatPrivate.ts
+++ b/server/data/ChatPrivate.ts
@@ -13,7 +13,7 @@ export default class ChatPrivate extends Chat {
 
     static createForPrivate(userA: User, userB: User) {
         const chat = this.create(this.getChatIdByUsersId(userA.bean.id, userB.bean.id), 'private')
-        chat.setMembers([
+        chat.addMembers([
             userA.bean.id,
             userB.bean.id
         ])
diff --git a/server/data/UserChatLinker.ts b/server/data/UserChatLinker.ts
new file mode 100644
index 0000000..0204a23
--- /dev/null
+++ b/server/data/UserChatLinker.ts
@@ -0,0 +1,50 @@
+import { DatabaseSync } from "node:sqlite"
+import path from 'node:path'
+
+import config from "../config.ts"
+import { SQLInputValue } from "node:sqlite";
+export default class UserChatLinker {
+    static database: DatabaseSync = this.init()
+
+    private static init(): DatabaseSync {
+        const db: DatabaseSync = new DatabaseSync(path.join(config.data_path, 'UserChatLinker.db'))
+        db.exec(`
+            CREATE TABLE IF NOT EXISTS UserChatLinker (
+                /* 序号 */ count INTEGER PRIMARY KEY AUTOINCREMENT,
+                /* 用戶 ID */ user_id TEXT NOT NULL,
+                /* Chat ID */ chat_id TEXT NOT NULL
+            );
+       `)
+        return db
+    }
+
+    /**
+     * 對用戶和對話建立關聯
+     * 自動檢測是否已關聯, 保證不會重複
+     */
+    static linkUserAndChat(userId: string, chatId: string) {
+        if (!this.checkUserIsLinkedToChat(userId, chatId))
+            this.database.prepare(`INSERT INTO UserChatLinker (
+                user_id,
+                chat_id
+            ) VALUES (?, ?);`).run(
+                userId,
+                chatId
+            )
+    }
+    static unlinkUserAndChat(userId: string, chatId: string) {
+        this.database.prepare(`DELETE FROM UserChatLinker WHERE user_id = ? AND chat_id = ?`).run(userId, chatId)
+    }
+    static checkUserIsLinkedToChat(userId: string, chatId: string) {
+        return this.findAllByCondition('user_id = ? AND chat_id = ?', userId, chatId).length != 0
+    }
+    static getUserChats(userId: string) {
+        return this.findAllByCondition('user_id = ?', userId).map((v) => v.chat_id) as string[]
+    }
+    static getChatMembers(chatId: string) {
+        return this.findAllByCondition('chat_id = ?', chatId).map((v) => v.user_id) as string[]
+    }
+    protected static findAllByCondition(condition: string, ...args: SQLInputValue[]) {
+        return this.database.prepare(`SELECT * FROM UserChatLinker WHERE ${condition}`).all(...args)
+    }
+}