diff --git a/src/main/java/com/teaching/backend/common/ErrorCode.java b/src/main/java/com/teaching/backend/common/ErrorCode.java
index 9679c72..808b0e5 100644
--- a/src/main/java/com/teaching/backend/common/ErrorCode.java
+++ b/src/main/java/com/teaching/backend/common/ErrorCode.java
@@ -33,6 +33,7 @@ public enum ErrorCode {
     CONTENT_EXISTS(41000, "内容存在"),
     STUDENT_ROLE_CANT_MULTIPLESEND(41001, "学生用户不能群发，只能单发"),
     LEAST_ONE_USER(41002, "最少选择一个用户"),
+    MOST_ONE_COURSE(41003, "您一次性最多只能在一个课程下发消息！"),
     KNOWS_EXISTS(41001, "存在关联的知识点"),
     ADD_RELATION_FAILED(41002, "添加关系失败"),
 
diff --git a/src/main/java/com/teaching/backend/controller/courses/CoursesController.java b/src/main/java/com/teaching/backend/controller/courses/CoursesController.java
index c42bb16..d53b0c5 100644
--- a/src/main/java/com/teaching/backend/controller/courses/CoursesController.java
+++ b/src/main/java/com/teaching/backend/controller/courses/CoursesController.java
@@ -140,7 +140,7 @@ public class CoursesController {
     }
 
     @ApiOperation("根据用户id，查询与用户有关的课程列表，并在课程列表显示所有用户信息")
-//    @ValidateParams({"userId"})
+    @ValidateParams({"userId"})
     @GetMapping("/page/courseusers")
     public BaseResponse<List<CourseUserInfVO>> getUserInfByCourse(@RequestParam Long userId){
         List<CourseUserInfVO> courseUsersInfList = coursesService.getUserInfByCourse(userId);
diff --git a/src/main/java/com/teaching/backend/controller/message/MessagesController.java b/src/main/java/com/teaching/backend/controller/message/MessagesController.java
index be95f7f..bfcf1c6 100644
--- a/src/main/java/com/teaching/backend/controller/message/MessagesController.java
+++ b/src/main/java/com/teaching/backend/controller/message/MessagesController.java
@@ -37,7 +37,7 @@ public class MessagesController {
     private IMessagesService messagesService;
 
     @ApiOperation("发送消息")
-    @ValidateParams({"senderId","title","content","receiverId"}) // 需要校验的参数
+    @ValidateParams({"senderId","title","content","receiverId","courseId"}) // 需要校验的参数
     @PostMapping("/addmessage")
     public BaseResponse<String> sendMessage(@RequestBody SysMessageDTO sysMessageDTO){
         String data = messagesService.sendMessageToUserInbox(sysMessageDTO);
diff --git a/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java b/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
index 6b7b2c4..7d1755e 100644
--- a/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
+++ b/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
@@ -59,6 +59,13 @@ public class MessagesServiceImpl extends ServiceImpl<MessagesMapper, SysMessages
             throw new BusinessException(ErrorCode.LEAST_ONE_USER);
         }
 
+        List<String> courseIds = Arrays.stream(sysMessageDTO.getCourseId().split(","))
+                .map(String::valueOf)
+                .collect(Collectors.toList());
+        if (courseIds.size()>1){
+            throw new BusinessException(ErrorCode.MOST_ONE_COURSE);
+        }
+
         // 4.判断是什么用户，只有教师可以群发，学生只能单发
         String roleId = umsUserMapper.selectOne(new LambdaQueryWrapper<>(UmsUser.class)
                 .eq(UmsUser::getId, sysMessageDTO.getSenderId())).getRoleId();