diff --git a/README.md b/README.md
index 3f8c98c..76cda93 100644
--- a/README.md
+++ b/README.md
@@ -168,10 +168,89 @@ 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
+
+<table>
+    <thead>
+        <td>秒</td>
+        <td>分</td>
+        <td>時</td>
+        <td>月中的日</td>
+        <td>週中的日</td>
+        <td>年</td>
+        <td>說明</td>
+    </thead>
+    <tbody>
+        <tr>
+            <td>0/30</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td>每30秒執行一次</td>
+        </tr>
+        <tr>
+            <td>30</td>
+            <td>9</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td style="color: red">每日早上09:30執行一次(UTC)</td>
+        </tr>
+        <tr>
+            <td>30</td>
+            <td>9</td>
+            <td>*</td>
+            <td>*</td>
+            <td>MON-FRI</td>
+            <td>*</td>
+            <td style="color: red">每週一到週五早上09:30執行一次(UTC)</td>
+        </tr>
+        <tr>
+            <td>30</td>
+            <td>09</td>
+            <td>*</td>
+            <td>1</td>
+            <td>*</td>
+            <td>*</td>
+            <td style="color: red">每月1號早上09:30執行一次(UTC)</td>
+        </tr>
+        <tr>
+            <td>0/30</td>
+            <td>0-30</td>
+            <td>9</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td style="color: red">每日早上09:00~09:30，每30秒執行一次(UTC)</td>
+        </tr>
+        <tr>
+            <td>0/30</td>
+            <td>*</td>
+            <td>9-12</td>
+            <td>*</td>
+            <td>*</td>
+            <td>*</td>
+            <td style="color: red">每日早上09:00~12:00，每30秒執行一次(UTC)</td>
+        </tr>
+        <tr>
+            <td>0/30</td>
+            <td>*</td>
+            <td>9-12</td>
+            <td>1-5</td>
+            <td>*</td>
+            <td>*</td>
+            <td style="color: red">每月1號到5號早上09:00~12:00，每30秒執行一次(UTC)</td>
+        </tr>
+    </tbody>
+</table>
+
 ```
 RecurringJob.AddOrUpdate("job_id", () => Console.Write("Recurring By CRON"), Cron.Daily);
 
-RecurringJob.AddOrUpdate("job_id", () => Console.Write("Recurring By CRON expressions"), "0 12 * */2");
+RecurringJob.AddOrUpdate("job_id", () => Console.Write("Recurring By CRON expressions"), "* 0/1 * * ? *");
 ```
 
 移除已存在的排程任務