diff --git a/app/controllers/courses_controller.rb b/app/controllers/courses_controller.rb
index a35860f2..221acf3c 100644
--- a/app/controllers/courses_controller.rb
+++ b/app/controllers/courses_controller.rb
@@ -2434,7 +2434,7 @@ class CoursesController < ApplicationController
       sheet1[count_row,column+=1] = member.user.login
       sheet1[count_row,column+=1] = member.user.mail
       sheet1[count_row,column+=1] = member.user.user_extensions.student_id
-      sheet1[count_row,column+=1] = member.course_group_id == 0 ? "暂无" : member.course_group.name
+      sheet1[count_row,column+=1] = member.course_group_id == 0 ? "暂无" : member.course_group.try(:name)
       # current_col = 5
       shixun_score = 0
       homeworks.where(:homework_type => 4).each do |homework|