diff --git a/dm/pkg/schema/tracker.go b/dm/pkg/schema/tracker.go
index f5b7b1950fc..c6bb88625c2 100644
--- a/dm/pkg/schema/tracker.go
+++ b/dm/pkg/schema/tracker.go
@@ -32,6 +32,7 @@ import (
 	"github.com/pingcap/tidb/pkg/parser/model"
 	"github.com/pingcap/tidb/pkg/parser/mysql"
 	"github.com/pingcap/tidb/pkg/sessionctx"
+	"github.com/pingcap/tidb/pkg/sessionctx/variable"
 	"github.com/pingcap/tidb/pkg/util/chunk"
 	"github.com/pingcap/tidb/pkg/util/filter"
 	"github.com/pingcap/tidb/pkg/util/mock"
@@ -465,6 +466,17 @@ func (dt *downstreamTracker) getTableInfoByCreateStmt(tctx *tcontext.Context, ta
 		return nil, dmterror.ErrSchemaTrackerInvalidCreateTableStmt.Delegate(err, createStr)
 	}
 
+	// suppress ErrTooLongKey
+	strictSQLModeBackup := dt.se.GetSessionVars().StrictSQLMode
+	dt.se.GetSessionVars().StrictSQLMode = false
+	// support drop PK
+	enableClusteredIndexBackup := dt.se.GetSessionVars().EnableClusteredIndex
+	dt.se.GetSessionVars().EnableClusteredIndex = variable.ClusteredIndexDefModeOff
+	defer func() {
+		dt.se.GetSessionVars().StrictSQLMode = strictSQLModeBackup
+		dt.se.GetSessionVars().EnableClusteredIndex = enableClusteredIndexBackup
+	}()
+
 	ti, err := ddl.BuildTableInfoWithStmt(dt.se, stmtNode.(*ast.CreateTableStmt), mysql.DefaultCharset, "", nil)
 	if err != nil {
 		return nil, dmterror.ErrSchemaTrackerCannotMockDownstreamTable.Delegate(err, createStr)
diff --git a/dm/pkg/schema/tracker_test.go b/dm/pkg/schema/tracker_test.go
index 3b04c8df5b9..f8780c7b7ad 100644
--- a/dm/pkg/schema/tracker_test.go
+++ b/dm/pkg/schema/tracker_test.go
@@ -613,7 +613,7 @@ func TestGetDownStreamIndexInfo(t *testing.T) {
 
 	mock.ExpectQuery("SHOW CREATE TABLE " + tableID).WillReturnRows(
 		sqlmock.NewRows([]string{"Table", "Create Table"}).
-			AddRow("test", "create table t(a int primary key, b int, c varchar(20000), key(c(20000)))"))
+			AddRow("test", "create table t(a int, b int, c varchar(20000), primary key(a, b), key(c(20000)))/*!90000 SHARD_ROW_ID_BITS=6 */"))
 	dti, err := tracker.GetDownStreamTableInfo(tcontext.Background(), tableID, oriTi)
 	require.NoError(t, err)
 	require.NotNil(t, dti.WhereHandle.UniqueNotNullIdx)