diff --git a/src/main/java/com/peanut/modules/common/service/impl/ClassEntityServiceImpl.java b/src/main/java/com/peanut/modules/common/service/impl/ClassEntityServiceImpl.java
index 79e432af..d421d1ed 100644
--- a/src/main/java/com/peanut/modules/common/service/impl/ClassEntityServiceImpl.java
+++ b/src/main/java/com/peanut/modules/common/service/impl/ClassEntityServiceImpl.java
@@ -644,7 +644,7 @@ public class ClassEntityServiceImpl extends ServiceImpl<ClassEntityDao, ClassEnt
         result.put("examStartTime","");
         result.put("examEndTime","");
         result.put("examEndDays","");
-        if (classModel.getIsExam()==1){
+        if (classModel.getIsExam()==1&&classEntity.getStartTime()!=null){
             Date examStartTime = DateUtils.addDateDays(classEntity.getStartTime(),classModel.getDays());
             result.put("examStartTime",DateUtils.stringToDate(DateUtils.format(examStartTime),"yyyy-MM-dd"));
             Date examEndTime = DateUtils.addDateDays(classEntity.getStartTime(),classModel.getDays()-1+classModel.getExamDays());