diff --git a/a8/types.h b/a8/types.h
index 00c10a8..4b03168 100644
--- a/a8/types.h
+++ b/a8/types.h
@@ -22,7 +22,7 @@ namespace a8
 
     const int TIMER_EXEC_EVENT = 1;
     const int TIMER_DELETE_EVENT = 2;
-    const int TIMER_DESTORY_EVNET = 3;
-    const int TIMER_USER_EVNET = 66;
+    const int TIMER_DESTORY_EVENT = 3;
+    const int TIMER_USER_EVENT = 66;
 
 };
diff --git a/a8/xtimer.cc b/a8/xtimer.cc
index 3d8d807..62b95cc 100644
--- a/a8/xtimer.cc
+++ b/a8/xtimer.cc
@@ -203,7 +203,7 @@ namespace a8
             }
         }
 
-        void InternalDelete(xtimer_list* timer)
+        void InternalDelete(xtimer_list* timer, bool is_destory, bool to_free_list)
         {
             if (!timer) {
                 abort();
@@ -211,13 +211,19 @@ namespace a8
             if (base_->running_timer == timer) {
                 base_->running_timer = nullptr;
             }
-            if (timer->cb) {
-                timer->cb(TIMER_DELETE_EVENT, nullptr);
-            }
             DetachTimer(timer);
             if (!list_empty(&timer->attach_entry)) {
                 list_del_init(&timer->attach_entry);
             }
+            if (is_destory) {
+                if (timer->cb) {
+                    timer->cb(TIMER_DESTORY_EVENT, nullptr);
+                }
+            } else {
+                if (timer->cb) {
+                    timer->cb(TIMER_DELETE_EVENT, nullptr);
+                }
+            }
             while (!list_empty(&timer->destory_handle_list)) {
                 XTimerDestoryHandleNode* node = list_first_entry(&timer->destory_handle_list,
                                                                  XTimerDestoryHandleNode,
@@ -226,7 +232,11 @@ namespace a8
                 node->cb(timer);
                 delete node;
             }
-            AddToFreeList(timer);
+            if (to_free_list) {
+                AddToFreeList(timer);
+            } else {
+                delete timer;
+            }
         }
 
         void InternalModifyTime(xtimer_list* timer, int expire_time)
@@ -284,22 +294,7 @@ namespace a8
                         switch (timer->timer_type) {
                         case kTimeOutTimer:
                             {
-                                DetachTimer(timer);
-                                if (!list_empty(&timer->attach_entry)) {
-                                    list_del_init(&timer->attach_entry);
-                                }
-                                while (!list_empty(&timer->destory_handle_list)) {
-                                    XTimerDestoryHandleNode* node = list_first_entry(&timer->destory_handle_list,
-                                                                                     XTimerDestoryHandleNode,
-                                                                                     entry);
-                                    list_del_init(&node->entry);
-                                    node->cb(timer);
-                                    delete node;
-                                }
-                                AddToFreeList(timer);
-                                if (timer->cb) {
-                                    timer->cb(TIMER_DELETE_EVENT, nullptr);
-                                }
+                                InternalDelete(timer, false, true);
                             }
                             break;
                         default:
@@ -315,7 +310,7 @@ namespace a8
 
         void DeleteCurrentTimer()
         {
-            InternalDelete(base_->running_timer);
+            InternalDelete(base_->running_timer, false, true);
         }
 
     private:
@@ -359,19 +354,7 @@ namespace a8
                     while (!list_empty(head)) {
                         struct xtimer_list *timer;
                         timer = list_first_entry(head, struct xtimer_list,entry);
-                        DetachTimer(timer);
-                        if (!list_empty(&timer->attach_entry)) {
-                            list_del_init(&timer->attach_entry);
-                        }
-                        while (!list_empty(&timer->destory_handle_list)) {
-                            XTimerDestoryHandleNode* node = list_first_entry(&timer->destory_handle_list,
-                                                                             XTimerDestoryHandleNode,
-                                                                             entry);
-                            list_del_init(&node->entry);
-                            node->cb(timer);
-                            delete node;
-                        }
-                        delete timer;
+                        InternalDelete(timer, true, false);
                     }
                 };
             for (int j = 0; j < TVN_SIZE; j++) {
@@ -528,7 +511,7 @@ namespace a8
         if (timer_wp.expired()) {
             abort();
         }
-        impl_->InternalDelete(timer_wp.lock()->timer);
+        impl_->InternalDelete(timer_wp.lock()->timer, false, true);
     }
 
     long long XTimer::GetRemainTime(XTimerWp& timer_wp)