diff --git a/app/api/mobile/apis/courses.rb b/app/api/mobile/apis/courses.rb
index 0ae3bba1d..d3f0e8cef 100644
--- a/app/api/mobile/apis/courses.rb
+++ b/app/api/mobile/apis/courses.rb
@@ -116,8 +116,15 @@ module Mobile
         delete ":id" do
           authenticate!
           cs = CoursesService.new
-          cs.exit_course({"object_id" => params[:id]}, current_user)
-          {status: 0}
+          status = cs.exit_course({:object_id => params[:id]}, current_user)
+          out = {status: status}
+          message = case status
+                      when 0; "退出成功"
+                      when 1; "您不在课程中"
+                      when 2; "您还未登录"
+                      else; "未知错误，请稍后再试"
+                    end
+          out.merge(message: message)
         end
 
         desc "搜索课程"
diff --git a/app/services/courses_service.rb b/app/services/courses_service.rb
index 23c25d302..d8dd8299b 100644
--- a/app/services/courses_service.rb
+++ b/app/services/courses_service.rb
@@ -197,14 +197,27 @@ class CoursesService
   #退出课程
   #object_id: 课程id
   #user：当前用户
+  #@state == 0 退出成功
+  #@state == 1 不在课程中
+  #@state == 2 您还未登录
+  #@state 其他 未知错误，请稍后再试
   def exit_course params,user
+    if user.nil?
+      @state = 2
+      return @state
+    end
     @member = Member.where('course_id = ? and user_id = ?', params[:object_id], user.id)
+    if @member.nil? || @member.count == 0
+      @state = 1
+      return @state
+    end
     @member.first.destroy
-
     joined = StudentsForCourse.where('student_id = ? and course_id = ?', user.id, params[:object_id])
     joined.each do |join|
       join.delete
+      @state = 0
     end
+    @state
   end
 
   #加入课程