diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
index 29a073936645c..e638b6d9f9305 100644
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@@ -813,7 +813,7 @@ var defaultSysVars = []*SysVar{
 	{Scope: ScopeGlobal, Name: TiDBGCRunInterval, Value: "10m0s", Type: TypeDuration, MinValue: int64(time.Minute * 10), MaxValue: math.MaxInt64},
 	{Scope: ScopeGlobal, Name: TiDBGCLifetime, Value: "10m0s", Type: TypeDuration, MinValue: int64(time.Minute * 10), MaxValue: math.MaxInt64},
 	{Scope: ScopeGlobal, Name: TiDBGCConcurrency, Value: "-1", Type: TypeInt, MinValue: 1, MaxValue: 128, AllowAutoValue: true},
-	{Scope: ScopeGlobal, Name: TiDBGCScanLockMode, Value: "PHYSICAL", Type: TypeEnum, PossibleValues: []string{"PHYSICAL", "LEGACY"}},
+	{Scope: ScopeGlobal, Name: TiDBGCScanLockMode, Value: "LEGACY", Type: TypeEnum, PossibleValues: []string{"PHYSICAL", "LEGACY"}},
 }
 
 // FeedbackProbability points to the FeedbackProbability in statistics package.