diff --git a/src/main/resources/mapper/tms/ClassTeachingDao.xml b/src/main/resources/mapper/tms/ClassTeachingDao.xml
index 6b40139..ebea109 100644
--- a/src/main/resources/mapper/tms/ClassTeachingDao.xml
+++ b/src/main/resources/mapper/tms/ClassTeachingDao.xml
@@ -21,6 +21,8 @@
 	        tms_experimental_teaching
         WHERE
             is_del=0
+        AND
+            start_time >='2020-01-01 00:00:00'
             <if test="cla.status!=null">and `status` = #{cla.status}</if>
             <if test="cla.condition!=null">and ( project_name like concat('%',#{cla.condition},'%') or experimental_class_name like concat('%',#{cla.condition},'%') )</if>
             <if test="cla.startTime!=null and cla.endTime!=null">and stop_time between #{cla.endTime} and #{cla.startTime}</if>