diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index ca8c8fb29c..025af08e30 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -40,6 +40,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-394 - Update scheduler unittest
 - MS-400 - Add timestamp record in task state change function
 - MS-402 - Add dump implementation for TaskTableItem
+- MS-404 - Release index after search task done avoid memory increment continues
 
 ## New Feature
 - MS-343 - Implement ResourceMgr
diff --git a/cpp/src/scheduler/task/SearchTask.cpp b/cpp/src/scheduler/task/SearchTask.cpp
index ea482bcb72..992e915f23 100644
--- a/cpp/src/scheduler/task/SearchTask.cpp
+++ b/cpp/src/scheduler/task/SearchTask.cpp
@@ -207,6 +207,9 @@ XSearchTask::Execute() {
     CollectDurationMetrics(index_type_, total_time);
 
     rc.ElapseFromBegin("totally cost");
+
+    // release index in resource
+    index_engine_ = nullptr;
 }
 
 TaskPtr