diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index 3c81868e32..83f1aa6998 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -104,6 +104,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-519 - Add event_test in scheduler
 - MS-520 - Update resource_test in scheduler
 - MS-524 - Add some unittest in event_test and resource_test
+- MS-525 - Disable parallel reduce in SearchTask
 
 ## New Feature
 - MS-343 - Implement ResourceMgr
diff --git a/cpp/src/scheduler/task/SearchTask.cpp b/cpp/src/scheduler/task/SearchTask.cpp
index aa526517fa..47d5532921 100644
--- a/cpp/src/scheduler/task/SearchTask.cpp
+++ b/cpp/src/scheduler/task/SearchTask.cpp
@@ -20,47 +20,47 @@ namespace engine {
 static constexpr size_t PARALLEL_REDUCE_THRESHOLD = 10000;
 static constexpr size_t PARALLEL_REDUCE_BATCH = 1000;
 
-bool
-NeedParallelReduce(uint64_t nq, uint64_t topk) {
-    server::ServerConfig &config = server::ServerConfig::GetInstance();
-    server::ConfigNode &db_config = config.GetConfig(server::CONFIG_DB);
-    bool need_parallel = db_config.GetBoolValue(server::CONFIG_DB_PARALLEL_REDUCE, false);
-    if (!need_parallel) {
-        return false;
-    }
-
-    return nq * topk >= PARALLEL_REDUCE_THRESHOLD;
-}
-
-void
-ParallelReduce(std::function<void(size_t, size_t)> &reduce_function, size_t max_index) {
-    size_t reduce_batch = PARALLEL_REDUCE_BATCH;
-
-    auto thread_count = std::thread::hardware_concurrency() - 1; //not all core do this work
-    if (thread_count > 0) {
-        reduce_batch = max_index / thread_count + 1;
-    }
-    ENGINE_LOG_DEBUG << "use " << thread_count <<
-                     " thread parallelly do reduce, each thread process " << reduce_batch << " vectors";
-
-    std::vector<std::shared_ptr<std::thread> > thread_array;
-    size_t from_index = 0;
-    while (from_index < max_index) {
-        size_t to_index = from_index + reduce_batch;
-        if (to_index > max_index) {
-            to_index = max_index;
-        }
-
-        auto reduce_thread = std::make_shared<std::thread>(reduce_function, from_index, to_index);
-        thread_array.push_back(reduce_thread);
-
-        from_index = to_index;
-    }
-
-    for (auto &thread_ptr : thread_array) {
-        thread_ptr->join();
-    }
-}
+//bool
+//NeedParallelReduce(uint64_t nq, uint64_t topk) {
+//    server::ServerConfig &config = server::ServerConfig::GetInstance();
+//    server::ConfigNode &db_config = config.GetConfig(server::CONFIG_DB);
+//    bool need_parallel = db_config.GetBoolValue(server::CONFIG_DB_PARALLEL_REDUCE, false);
+//    if (!need_parallel) {
+//        return false;
+//    }
+//
+//    return nq * topk >= PARALLEL_REDUCE_THRESHOLD;
+//}
+//
+//void
+//ParallelReduce(std::function<void(size_t, size_t)> &reduce_function, size_t max_index) {
+//    size_t reduce_batch = PARALLEL_REDUCE_BATCH;
+//
+//    auto thread_count = std::thread::hardware_concurrency() - 1; //not all core do this work
+//    if (thread_count > 0) {
+//        reduce_batch = max_index / thread_count + 1;
+//    }
+//    ENGINE_LOG_DEBUG << "use " << thread_count <<
+//                     " thread parallelly do reduce, each thread process " << reduce_batch << " vectors";
+//
+//    std::vector<std::shared_ptr<std::thread> > thread_array;
+//    size_t from_index = 0;
+//    while (from_index < max_index) {
+//        size_t to_index = from_index + reduce_batch;
+//        if (to_index > max_index) {
+//            to_index = max_index;
+//        }
+//
+//        auto reduce_thread = std::make_shared<std::thread>(reduce_function, from_index, to_index);
+//        thread_array.push_back(reduce_thread);
+//
+//        from_index = to_index;
+//    }
+//
+//    for (auto &thread_ptr : thread_array) {
+//        thread_ptr->join();
+//    }
+//}
 
 void
 CollectFileMetrics(int file_type, size_t file_size) {
@@ -238,11 +238,11 @@ Status XSearchTask::ClusterResult(const std::vector<long> &output_ids,
         }
     };
 
-    if (NeedParallelReduce(nq, topk)) {
-        ParallelReduce(reduce_worker, nq);
-    } else {
+//    if (NeedParallelReduce(nq, topk)) {
+//        ParallelReduce(reduce_worker, nq);
+//    } else {
         reduce_worker(0, nq);
-    }
+//    }
 
     return Status::OK();
 }
@@ -343,11 +343,11 @@ Status XSearchTask::TopkResult(SearchContext::ResultSet &result_src,
         }
     };
 
-    if (NeedParallelReduce(result_src.size(), topk)) {
-        ParallelReduce(ReduceWorker, result_src.size());
-    } else {
+//    if (NeedParallelReduce(result_src.size(), topk)) {
+//        ParallelReduce(ReduceWorker, result_src.size());
+//    } else {
         ReduceWorker(0, result_src.size());
-    }
+//    }
 
     return Status::OK();
 }