diff --git a/app/controllers/courses_controller.rb b/app/controllers/courses_controller.rb
index 221acf3c..b830776b 100644
--- a/app/controllers/courses_controller.rb
+++ b/app/controllers/courses_controller.rb
@@ -2550,7 +2550,7 @@ class CoursesController < ApplicationController
       sheet2[count_row,1] = act_member.user.show_real_name
       sheet2[count_row,2] = act_member.user.login
       sheet2[count_row,3] = act_member.user.user_extensions.student_id
-      sheet2[count_row,4] = act_member.course_group_id == 0 ? "暂无" : act_member.course_group.name
+      sheet2[count_row,4] = act_member.course_group_id == 0 ? "暂无" : act_member.course_group.try(:name)
       sheet2[count_row,5]= act_member.homework_num.to_i + act_member.graduation_num.to_i
       sheet2[count_row,6]= act_member.exercise_num
       sheet2[count_row,7]= act_member.poll_num