diff --git a/src/ai/movegen.cpp b/src/ai/movegen.cpp
index 9fdfee8d..bbb8c27f 100644
--- a/src/ai/movegen.cpp
+++ b/src/ai/movegen.cpp
@@ -39,6 +39,13 @@ void StateInfo::generateChildren(const Stack<move_t, MOVE_COUNT> &moves,
 
     assert(size != 0);
 
+    if (node->childrenSize > 0) {
+        for (int i = 0; i < size; i++) {
+            ai->deleteTree(node->children[i]);
+        }
+        node->childrenSize = 0;
+    }
+
     for (int i  = 0; i < size; i++) {
         node->addChild(moves[i], ai, this
 #ifdef BEST_MOVE_ENABLE
diff --git a/src/ai/search.h b/src/ai/search.h
index 1110f932..108fc932 100644
--- a/src/ai/search.h
+++ b/src/ai/search.h
@@ -226,7 +226,6 @@ public: /* TODO: Move to private or protected */
     // 结点个数;
     size_t nodeCount { 0 };
 
-protected:
     // 对合法的着法降序排序
     void sortMoves(Node *node);