diff --git a/app/helpers/exercise_helper.rb b/app/helpers/exercise_helper.rb
index 6f39d8f8a..db45e8d87 100644
--- a/app/helpers/exercise_helper.rb
+++ b/app/helpers/exercise_helper.rb
@@ -14,17 +14,18 @@ module ExerciseHelper
   # 多选
   def multiselect_standard_answer(params)
     size = params.ord - 96
-    answer = ""
+    answer = []
     if size > 0 # 小写字母答案
       for i in 0..(params.length-1)
-        answer += (params[i].ord - 96).to_s
+        answer << (params[i].ord - 96).to_s
       end
     else
       for i in 0..(params.length-1)
-        answer += (params[i].ord - 64).to_s
+        answer << (params[i].ord - 64)
       end
     end
-    answer.to_i
+    answer = answer.sort
+    answer.join("")
   end
 
   def fill_standart_answer(params, standart_answer)