diff --git a/parser/ast/expressions.go b/parser/ast/expressions.go
index 67b7383e57c04..b1bda01a5e88e 100755
--- a/parser/ast/expressions.go
+++ b/parser/ast/expressions.go
@@ -289,13 +289,14 @@ func (n *CaseExpr) Restore(ctx *RestoreCtx) error {
 
 // Format the ExprNode into a Writer.
 func (n *CaseExpr) Format(w io.Writer) {
-	fmt.Fprint(w, "CASE ")
+	fmt.Fprint(w, "CASE")
 	// Because the presence of `case when` syntax, `Value` could be nil and we need check this.
 	if n.Value != nil {
-		n.Value.Format(w)
 		fmt.Fprint(w, " ")
+		n.Value.Format(w)
 	}
 	for _, clause := range n.WhenClauses {
+		fmt.Fprint(w, " ")
 		fmt.Fprint(w, "WHEN ")
 		clause.Expr.Format(w)
 		fmt.Fprint(w, " THEN ")
diff --git a/parser/ast/format_test.go b/parser/ast/format_test.go
index 43d7b2703477b..aca579740fdf8 100644
--- a/parser/ast/format_test.go
+++ b/parser/ast/format_test.go
@@ -84,6 +84,7 @@ func (ts *testAstFormatSuite) TestAstFormat(c *C) {
 		{` cast( a as decimal ) `, "CAST(`a` AS DECIMAL(11))"},
 		{` cast( a as decimal (3) ) `, "CAST(`a` AS DECIMAL(3))"},
 		{` cast( a as decimal (3,3) ) `, "CAST(`a` AS DECIMAL(3, 3))"},
+		{` ((case when (c0 = 0) then 0 when (c0 > 0) then (c1 / c0) end)) `, "((CASE WHEN (`c0` = 0) THEN 0 WHEN (`c0` > 0) THEN (`c1` / `c0`) END))"},
 		{` convert (a, signed) `, "CONVERT(`a`, SIGNED)"},
 		{` binary "hello"`, `BINARY "hello"`},
 	}