diff --git a/conf/config.toml b/conf/config.toml
index 0c4acf5fd8c..438d2c857a5 100644
--- a/conf/config.toml
+++ b/conf/config.toml
@@ -111,9 +111,9 @@
 
 [schedule]
 ## Controls the size limit of Region Merge.
-# max-merge-region-size = 54
+# max-merge-region-size = 20
 ## Specifies the upper limit of the Region Merge key.
-# max-merge-region-keys = 540000
+# max-merge-region-keys = 200000
 ## Controls the time interval between the split and merge operations on the same Region.
 # split-merge-interval = "1h"
 ## When PD fails to receive the heartbeat from a store after the specified period of time,
diff --git a/pkg/schedule/config/config.go b/pkg/schedule/config/config.go
index 124bff0a704..9074fce8fb8 100644
--- a/pkg/schedule/config/config.go
+++ b/pkg/schedule/config/config.go
@@ -28,13 +28,10 @@ import (
 
 const (
 	// DefaultMaxReplicas is the default number of replicas for each region.
-	DefaultMaxReplicas         = 3
-	defaultMaxSnapshotCount    = 64
-	defaultMaxPendingPeerCount = 64
-	// defaultMaxMergeRegionSize is the default maximum size of region when regions can be merged.
-	// After https://github.com/tikv/tikv/issues/17309, the default value is enlarged from 20 to 54,
-	// to make it compatible with the default value of region size of tikv.
-	defaultMaxMergeRegionSize     = 54
+	DefaultMaxReplicas            = 3
+	defaultMaxSnapshotCount       = 64
+	defaultMaxPendingPeerCount    = 64
+	defaultMaxMergeRegionSize     = 20
 	defaultLeaderScheduleLimit    = 4
 	defaultRegionScheduleLimit    = 2048
 	defaultWitnessScheduleLimit   = 4
diff --git a/tools/pd-ctl/tests/config/config_test.go b/tools/pd-ctl/tests/config/config_test.go
index 0404796a81e..ad91e759fa8 100644
--- a/tools/pd-ctl/tests/config/config_test.go
+++ b/tools/pd-ctl/tests/config/config_test.go
@@ -180,11 +180,9 @@ func (suite *configTestSuite) checkConfig(cluster *pdTests.TestCluster) {
 	scheduleConfig.MaxMergeRegionKeys = scheduleConfig.GetMaxMergeRegionKeys()
 	re.Equal(scheduleConfig, &scheduleCfg)
 
-	// After https://github.com/tikv/tikv/issues/17309, the default value is enlarged from 20 to 54,
-	// to make it compatible with the default value of region size of tikv.
-	re.Equal(54, int(svr.GetScheduleConfig().MaxMergeRegionSize))
+	re.Equal(20, int(svr.GetScheduleConfig().MaxMergeRegionSize))
 	re.Equal(0, int(svr.GetScheduleConfig().MaxMergeRegionKeys))
-	re.Equal(54*10000, int(svr.GetScheduleConfig().GetMaxMergeRegionKeys()))
+	re.Equal(20*10000, int(svr.GetScheduleConfig().GetMaxMergeRegionKeys()))
 
 	// set max-merge-region-size to 40MB
 	args = []string{"-u", pdAddr, "config", "set", "max-merge-region-size", "40"}
diff --git a/tools/pd-ctl/tests/region/region_test.go b/tools/pd-ctl/tests/region/region_test.go
index 49f1eaa0a58..afffba411bc 100644
--- a/tools/pd-ctl/tests/region/region_test.go
+++ b/tools/pd-ctl/tests/region/region_test.go
@@ -142,7 +142,7 @@ func TestRegion(t *testing.T) {
 		// region check empty-region command
 		{[]string{"region", "check", "empty-region"}, []*core.RegionInfo{r1}},
 		// region check undersized-region command
-		{[]string{"region", "check", "undersized-region"}, []*core.RegionInfo{r1, r3, r4}},
+		{[]string{"region", "check", "undersized-region"}, []*core.RegionInfo{r1, r4}},
 		// region check oversized-region command
 		{[]string{"region", "check", "oversized-region"}, []*core.RegionInfo{r2}},
 		// region keys --format=raw <start_key> <end_key> <limit> command