diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8830194ac4fe2f1ff7a22e65b19506f0fcb694b..9baa62a78d1b20a218796589ad5e233db0ff862b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,6 +50,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - \#649 - Typo "partiton" should be "partition"
 - \#654 - Random crash when frequently insert vector one by one
 - \#658 - Milvus error out when building SQ8H index without GPU resources
+- \#670 - Random failure of unittest db_test::SEARCH_TEST
 
 ## Feature
 - \#12 - Pure CPU version for Milvus
diff --git a/core/unittest/db/test_db.cpp b/core/unittest/db/test_db.cpp
index 768687a8a3d75693033049f9602a9c4203c35284..dbed92b355e0ec838e5e314ba7efdf923a61718c 100644
--- a/core/unittest/db/test_db.cpp
+++ b/core/unittest/db/test_db.cpp
@@ -338,7 +338,13 @@ TEST_F(DBTest, SEARCH_TEST) {
 
     {  // search by specify index file
         milvus::engine::meta::DatesT dates;
-        std::vector<std::string> file_ids = {"1", "2", "3", "4", "5", "6"};
+        std::vector<std::string> file_ids;
+        // sometimes this case run fast to merge file and build index, old file will be deleted immediately,
+        // so the QueryByFileID cannot get files to search
+        // input 100 files ids to avoid random failure of this case
+        for (int i = 0; i < 100; i++) {
+            file_ids.push_back(std::to_string(i));
+        }
         milvus::engine::ResultIds result_ids;
         milvus::engine::ResultDistances result_distances;
         stat = db_->QueryByFileID(TABLE_NAME, file_ids, k, nq, 10, xq.data(), dates, result_ids, result_distances);