diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
index 4a7fbee5..c9b1dd7c 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
@@ -185,7 +185,12 @@ public class Spider implements Runnable, Task {
      */
     public Spider setScheduler(Scheduler scheduler) {
         checkIfRunning();
+        Scheduler oldScheduler = this.scheduler;
         this.scheduler = scheduler;
+        Request request;
+        while ((request = oldScheduler.poll(this)) != null) {
+            this.scheduler.push(request, this);
+        }
         return this;
     }