diff --git a/apps/backend/src/bootstrap/loaders/express.ts b/apps/backend/src/bootstrap/loaders/express.ts
index 32b43ba2e..04dbaf99a 100644
--- a/apps/backend/src/bootstrap/loaders/express.ts
+++ b/apps/backend/src/bootstrap/loaders/express.ts
@@ -68,6 +68,18 @@ export default async (
           isAuthenticated: req.isAuthenticated(),
           logout: (callback: (err: any) => void) => req.logout(callback),
         },
+        // user: req.user
+        // ? {
+        //     ...req.user,
+        //     isAuthenticated: req.isAuthenticated(),
+        //     logout: (callback: (err: any) => void) => req.logout(callback),
+        //   }
+        // : {
+        //     id: "testUserId123",
+        //     role: "admin",
+        //     isAuthenticated: true,  // 让 auth 解析器认为用户已登录
+        //     logout: (callback: (err: any) => void) => callback(null),
+        //   },
       }),
     })
   );
diff --git a/apps/backend/src/modules/discussion/discussionController.ts b/apps/backend/src/modules/discussion/discussionController.ts
new file mode 100644
index 000000000..818dcc2c8
--- /dev/null
+++ b/apps/backend/src/modules/discussion/discussionController.ts
@@ -0,0 +1,39 @@
+import {DiscussionModel} from "@repo/common"
+import {formatPost} from "./formater"
+
+export const getDiscussions = async (courseNumber: string) => {
+    const discussion = await DiscussionModel.findOne({courseNumber: courseNumber});
+    if (!discussion) {
+        return { courseNumber, posts: [] };
+    }
+    const discussionObject = discussion.toObject(); 
+    return {
+        courseNumber: discussionObject.courseNumber,
+        posts: discussionObject.posts.map(formatPost)};
+};
+
+export const addPost = async(
+    courseNumber: string,  
+    PostContent: string,
+    context: any
+) => {
+    const userId = context.user.id;
+    const updatedPost = await DiscussionModel.findOneAndUpdate(
+        { courseNumber },
+        {
+            $push: {  
+                posts: {
+                    userId,
+                    PostContent,
+                }
+            }
+        },
+        { new: true, upsert: true }
+    );
+    if (!updatedPost) {
+        throw new Error("Failed to update or create the discussion post.");
+    }
+    const updatedPostObj = updatedPost.toObject();
+    const lastPost = updatedPostObj.posts[updatedPostObj.posts.length - 1];
+    return formatPost(lastPost);
+};
\ No newline at end of file
diff --git a/apps/backend/src/modules/discussion/formater.ts b/apps/backend/src/modules/discussion/formater.ts
new file mode 100644
index 000000000..d0545b66e
--- /dev/null
+++ b/apps/backend/src/modules/discussion/formater.ts
@@ -0,0 +1,5 @@
+export const formatPost = (post:any) => ({
+    userId: post.userId.toString(),
+    PostTime: post.PostTime.toISOString(),
+    PostContent: post.PostContent,
+});
diff --git a/apps/backend/src/modules/discussion/index.ts b/apps/backend/src/modules/discussion/index.ts
new file mode 100644
index 000000000..921091e1b
--- /dev/null
+++ b/apps/backend/src/modules/discussion/index.ts
@@ -0,0 +1,8 @@
+import resolver from "./resolver";
+import typeDef from "./typedefs/discussion";
+
+export default {
+    resolver,
+    typeDef,
+};
+  
\ No newline at end of file
diff --git a/apps/backend/src/modules/discussion/resolver.ts b/apps/backend/src/modules/discussion/resolver.ts
new file mode 100644
index 000000000..2d57fe330
--- /dev/null
+++ b/apps/backend/src/modules/discussion/resolver.ts
@@ -0,0 +1,21 @@
+import { getDiscussions, addPost } from "./discussionController";
+import {DiscussionModule} from "./generated-types/module-types"
+
+const resolvers: DiscussionModule.Resolvers = {
+    Query: {
+        discussions: async (_, {courseNumber}) => {
+            return await getDiscussions(courseNumber); 
+        }
+    },
+    Mutation: {
+        post: async (
+            _, 
+            { courseNumber, PostContent},
+            context) => {
+            return await addPost(courseNumber, PostContent, context); 
+        }
+    }
+};
+
+export default resolvers;
+
diff --git a/apps/backend/src/modules/discussion/typedefs/discussion.ts b/apps/backend/src/modules/discussion/typedefs/discussion.ts
new file mode 100644
index 000000000..e9bbc6445
--- /dev/null
+++ b/apps/backend/src/modules/discussion/typedefs/discussion.ts
@@ -0,0 +1,25 @@
+import { gql } from "graphql-tag";
+
+export default gql`
+    scalar courseNumber
+
+    type Query {
+        discussions(courseNumber:courseNumber!): Discussion
+    }
+
+    type Post {
+        userId: String!
+        PostTime: String!
+        PostContent: String!
+    }
+
+    type Discussion {
+        courseNumber: courseNumber!
+        posts: [Post!]
+    }
+
+    type Mutation {
+        post(courseNumber: courseNumber!, PostContent: String!): Post! @auth
+    }
+
+`;
\ No newline at end of file
diff --git a/apps/backend/src/modules/index.ts b/apps/backend/src/modules/index.ts
index 406f69a7d..dcbc02f30 100644
--- a/apps/backend/src/modules/index.ts
+++ b/apps/backend/src/modules/index.ts
@@ -9,6 +9,7 @@ import GradeDistribution from "./grade-distribution";
 import Schedule from "./schedule";
 import Term from "./term";
 import User from "./user";
+import Discussion from "./discussion";
 
 const modules = [
   User,
@@ -20,6 +21,7 @@ const modules = [
   Course,
   Class,
   Enrollment,
+  Discussion
 ];
 
 export const resolvers = merge(modules.map((module) => module.resolver));
diff --git a/packages/common/src/models/discussion.ts b/packages/common/src/models/discussion.ts
new file mode 100644
index 000000000..e49a31bb1
--- /dev/null
+++ b/packages/common/src/models/discussion.ts
@@ -0,0 +1,30 @@
+import mongoose, { Schema, Document, Model } from "mongoose";
+
+interface Post {
+    userId: string; 
+    PostContent: string; 
+    PostTime: Date;  
+}
+export interface DiscussionInfo extends Document {
+    courseNumber: string;
+    posts: Post[];
+}
+
+const postSchema: Schema = new Schema({
+    _id: { type: mongoose.Schema.Types.ObjectId, auto: true },
+    userId: { type: String, required: true }, //connect user?
+    PostTime: { type: Date, default: Date.now },
+    PostContent: { type: String, required: true },
+});
+
+const discussionSchema: Schema<DiscussionInfo> = new Schema({
+    courseNumber: { type: String, required: true },
+    posts: { type: [postSchema], default: []},
+});
+
+export const DiscussionModel: Model<DiscussionInfo> = mongoose.model<DiscussionInfo>(
+    "Discussion",
+    discussionSchema
+);
+
+
diff --git a/packages/common/src/models/index.ts b/packages/common/src/models/index.ts
index 093715fb0..30cbe02fc 100644
--- a/packages/common/src/models/index.ts
+++ b/packages/common/src/models/index.ts
@@ -6,3 +6,4 @@ export * from "./course";
 export * from "./section";
 export * from "./grade-distribution";
 export * from "./enrollment-history";
+export * from "./discussion";
\ No newline at end of file