diff --git a/BUILD_DOC.md b/BUILD_DOC.md
index b54487061..cb55cd32d 100644
--- a/BUILD_DOC.md
+++ b/BUILD_DOC.md
@@ -191,7 +191,7 @@ $mvn package -Dmaven.test.skip=true
 - 创建crontab并运行脚本. Create crontab and run the command.
 ```
 > crontab -e
-# 此处为每20分钟执行start-analysis.sh脚本. Executed start-analysis script every 20 minutes 
+# 此处为每20分钟执行start-analysis.sh脚本,Crontab表达式见[更多](http://tool.lu/crontab/). Executed start-analysis script every 20 minutes，Crontab express:[more](http://tool.lu/crontab/)
 */20 * * * * start-analysis.sh
 ```