diff --git a/cpp/src/server/RequestTask.cpp b/cpp/src/server/RequestTask.cpp
index e553c036da95d0f0ad637b2da1467a5bc89fe83b..d6c1a2fb9c0594aba32691ea7be0f6cba797e051 100644
--- a/cpp/src/server/RequestTask.cpp
+++ b/cpp/src/server/RequestTask.cpp
@@ -513,7 +513,7 @@ ServerError SearchVectorTaskBase::OnExecute() {
             return SetError(res, "Invalid table name: " + table_name_);
         }
 
-        if(top_k_ <= 0) {
+        if(top_k_ <= 0 || top_k_ > 1024) {
             return SetError(SERVER_INVALID_TOPK, "Invalid topk: " + std::to_string(top_k_));
         }
         if(record_array_.empty()) {