diff --git a/README.md b/README.md
index 76cda93..6f597c2 100644
--- a/README.md
+++ b/README.md
@@ -168,7 +168,7 @@ BackgroundJob.Schedule(() => Console.WriteLine("Delayed"), TimeSpan.FromDays(1))
 
 * Recurring jobs: 依照指定間隔，將任務丟入執行佇列
 
-Cron Expression
+Cron Expression [測試](https://crontab.guru/)
 
 <table>
     <thead>