diff --git a/NineChess/src/aithread.cpp b/NineChess/src/aithread.cpp
index 9df0ced2..3f4a5e25 100644
--- a/NineChess/src/aithread.cpp
+++ b/NineChess/src/aithread.cpp
@@ -35,7 +35,8 @@ void AiThread::setAi(const NineChess &chess)
     ai_ab.setChess(*(this->chess_));
 
 #ifdef HASH_MAP_ENABLE
-    //ai_ab.clearHashMap();
+    // TODO: 下第二盘时不明原因变慢，临时方案为清除哈希表
+    ai_ab.clearHashMap();
 #endif
 
     mutex.unlock();
diff --git a/NineChess/src/hashmap.h b/NineChess/src/hashmap.h
index de67f252..6c7cc320 100644
--- a/NineChess/src/hashmap.h
+++ b/NineChess/src/hashmap.h
@@ -97,16 +97,19 @@ namespace CTSL //Concurrent Thread Safe Library
 #endif
             }   
 
-#ifndef DISABLE_HASHBUCKET
+
             //Function to clean up the hasp map, i.e., remove all entries from it
             void clear()
             {
+#ifdef DISABLE_HASHBUCKET
+                memset(hashTable, 0, sizeof(HashNode<K, V>) * hashSize);
+#else
                 for(size_t i = 0; i < hashSize; i++)
                 {
                     (hashTable[i]).clear();
                 }
-            }  
 #endif
+            } 
 
         private:
 #ifdef DISABLE_HASHBUCKET
diff --git a/NineChess/src/ninechessai_ab.cpp b/NineChess/src/ninechessai_ab.cpp
index 1b50ad81..beb782e8 100644
--- a/NineChess/src/ninechessai_ab.cpp
+++ b/NineChess/src/ninechessai_ab.cpp
@@ -1007,7 +1007,7 @@ int NineChessAi_ab::recordHash(int value, int alpha, int beta, int depth, HashTy
 void NineChessAi_ab::clearHashMap()
 {
     //hashMapMutex.lock();
-    //hashmap.clear();
+    hashmap.clear();
     //hashMapMutex.unlock();
 }
 #endif /* HASH_MAP_ENABLE */