diff --git a/dm/syncer/opt_sharding_group.go b/dm/syncer/opt_sharding_group.go
index d87514371ea..ce4060de642 100644
--- a/dm/syncer/opt_sharding_group.go
+++ b/dm/syncer/opt_sharding_group.go
@@ -233,3 +233,11 @@ func (k *OptShardingGroupKeeper) RemoveSchema(schema string) {
 		}
 	}
 }
+
+// Reset resets the keeper.
+func (k *OptShardingGroupKeeper) Reset() {
+	k.Lock()
+	defer k.Unlock()
+	k.groups = make(map[string]*OptShardingGroup)
+	k.shardingReSyncs = make(map[string]binlog.Location)
+}
diff --git a/dm/syncer/opt_sharding_group_test.go b/dm/syncer/opt_sharding_group_test.go
index 88ad02cb873..9cd4eec7e6e 100644
--- a/dm/syncer/opt_sharding_group_test.go
+++ b/dm/syncer/opt_sharding_group_test.go
@@ -73,6 +73,11 @@ func (s *optShardingGroupSuite) TestLowestFirstPosInOptGroups() {
 	k.removeShardingReSync(&ShardingReSync{targetTable: utils.UnpackTableID(db2tbl)})
 	// should be pos11 now, pos21 is totally resolved
 	require.Equal(s.T(), pos11.Position, k.lowestFirstLocationInGroups().Position)
+
+	// reset
+	k.Reset()
+	require.Len(s.T(), k.groups, 0)
+	require.Len(s.T(), k.shardingReSyncs, 0)
 }
 
 func (s *optShardingGroupSuite) TestSync() {
diff --git a/dm/syncer/syncer.go b/dm/syncer/syncer.go
index 78a174cf71d..8c70946b3fd 100644
--- a/dm/syncer/syncer.go
+++ b/dm/syncer/syncer.go
@@ -649,6 +649,7 @@ func (s *Syncer) reset() {
 		s.sgk.ResetGroups()
 		s.pessimist.Reset()
 	case config.ShardOptimistic:
+		s.osgk.Reset()
 		s.optimist.Reset()
 	}
 }