diff --git a/distsql/distsql_test.go b/distsql/distsql_test.go
index 5a5cfa8230db1..2d47892f4fc12 100644
--- a/distsql/distsql_test.go
+++ b/distsql/distsql_test.go
@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/statistics"
 	"github.com/pingcap/tidb/store/tikv"
+	"github.com/pingcap/tidb/store/tikv/tikvrpc"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/codec"
@@ -179,6 +180,17 @@ func (s *testSuite) TestSelectResultRuntimeStats(c *C) {
 	c.Assert(stats.String(), Equals, expect)
 	// Test for idempotence.
 	c.Assert(stats.String(), Equals, expect)
+
+	s1.rpcStat.Stats[tikvrpc.CmdCop] = &tikv.RPCRuntimeStats{
+		Count:   1,
+		Consume: int64(time.Second),
+	}
+	stmtStats.RegisterStats(2, s1)
+	stats = stmtStats.GetRootStats(2)
+	expect = "cop_task: {num: 2, max: 1s, min: 1ms, avg: 500.5ms, p95: 1s, max_proc_keys: 200, p95_proc_keys: 200, tot_proc: 1s, tot_wait: 1s, rpc_num: 1, rpc_time: 1s, copr_cache_hit_ratio: 0.00}, backoff{RegionMiss: 1ms}"
+	c.Assert(stats.String(), Equals, expect)
+	// Test for idempotence.
+	c.Assert(stats.String(), Equals, expect)
 }
 
 func (s *testSuite) createSelectStreaming(batch, totalRows int, c *C) (*streamResult, []*types.FieldType) {
diff --git a/distsql/select_result.go b/distsql/select_result.go
index 61853c7e2687f..e819b2e890550 100644
--- a/distsql/select_result.go
+++ b/distsql/select_result.go
@@ -387,6 +387,7 @@ func (s *selectResultRuntimeStats) Merge(rs execdetails.RuntimeStats) {
 
 func (s *selectResultRuntimeStats) String() string {
 	buf := bytes.NewBuffer(nil)
+	rpcStat := s.rpcStat
 	if len(s.copRespTime) > 0 {
 		size := len(s.copRespTime)
 		if size == 1 {
@@ -424,9 +425,10 @@ func (s *selectResultRuntimeStats) String() string {
 				}
 			}
 		}
-		copRPC := s.rpcStat.Stats[tikvrpc.CmdCop]
+		copRPC := rpcStat.Stats[tikvrpc.CmdCop]
 		if copRPC != nil && copRPC.Count > 0 {
-			delete(s.rpcStat.Stats, tikvrpc.CmdCop)
+			rpcStat = rpcStat.Clone()
+			delete(rpcStat.Stats, tikvrpc.CmdCop)
 			buf.WriteString(", rpc_num: ")
 			buf.WriteString(strconv.FormatInt(copRPC.Count, 10))
 			buf.WriteString(", rpc_time: ")
@@ -437,7 +439,7 @@ func (s *selectResultRuntimeStats) String() string {
 		buf.WriteString("}")
 	}
 
-	rpcStatsStr := s.rpcStat.String()
+	rpcStatsStr := rpcStat.String()
 	if len(rpcStatsStr) > 0 {
 		buf.WriteString(", ")
 		buf.WriteString(rpcStatsStr)
diff --git a/store/tikv/region_request.go b/store/tikv/region_request.go
index fbd7f1d5f75fe..8d563870f1e18 100644
--- a/store/tikv/region_request.go
+++ b/store/tikv/region_request.go
@@ -98,6 +98,18 @@ func (r *RegionRequestRuntimeStats) String() string {
 	return buf.String()
 }
 
+// Clone returns a copy of itself.
+func (r *RegionRequestRuntimeStats) Clone() RegionRequestRuntimeStats {
+	newRs := NewRegionRequestRuntimeStats()
+	for cmd, v := range r.Stats {
+		newRs.Stats[cmd] = &RPCRuntimeStats{
+			Count:   v.Count,
+			Consume: v.Consume,
+		}
+	}
+	return newRs
+}
+
 // Merge merges other RegionRequestRuntimeStats.
 func (r *RegionRequestRuntimeStats) Merge(rs RegionRequestRuntimeStats) {
 	for cmd, v := range rs.Stats {