diff --git a/pkg/tree/tree.go b/pkg/tree/tree.go
index 100e46d..9f11281 100644
--- a/pkg/tree/tree.go
+++ b/pkg/tree/tree.go
@@ -1,10 +1,20 @@
 package tree
 
+import (
+	"regexp"
+)
+
 type Node[T any] struct {
 	Data     T         `json:"data"`
 	Children []Node[T] `json:"children"`
 }
 
+func Length(code string) int {
+	re := regexp.MustCompile(`[A-Z]\d+`)
+	match := re.FindString(code)
+	return len(match)
+}
+
 // 适用 A00001B00001 层级结构
 // parent 父级字符串
 // length A00001 一个节点长度
@@ -27,15 +37,18 @@ func Tree[T any](data []T, parent string, length int, pathFunc func(d T) string)
 }
 
 // 拆分层级结构 A00001B00001C00001 拆分为 ["A00001","A00001B00001","A00001B00001C00001"]
-// length A00001 一个节点长度
-func Split(code string, length int) (res []string) {
-	if len(code) < length {
+func Split(code string) (res []string) {
+	if code == "" {
+		return []string{}
+	}
+	l := Length(code)
+	if len(code) < l {
 		return
 	}
 
-	times := len(code) / length
+	times := len(code) / l
 	for i := 0; i < times; i++ {
-		res = append(res, code[:len(code)-length*i])
+		res = append(res, code[:len(code)-l*i])
 	}
 	return
 }
diff --git a/pkg/tree/tree_test.go b/pkg/tree/tree_test.go
index 2912490..44e9307 100644
--- a/pkg/tree/tree_test.go
+++ b/pkg/tree/tree_test.go
@@ -7,8 +7,7 @@ import (
 
 func TestSplit(t *testing.T) {
 	type args struct {
-		code   string
-		length int
+		code string
 	}
 	tests := []struct {
 		name    string
@@ -18,15 +17,28 @@ func TestSplit(t *testing.T) {
 		{
 			name: "test1",
 			args: args{
-				code:   "A00001B00001C00001",
-				length: 6,
+				code: "A00001B00001C00001",
 			},
 			wantRes: []string{"A00001B00001C00001", "A00001B00001", "A00001"},
 		},
+		{
+			name: "test2",
+			args: args{
+				code: "A001",
+			},
+			wantRes: []string{"A001"},
+		},
+		{
+			name: "test3",
+			args: args{
+				code: "",
+			},
+			wantRes: []string{},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if gotRes := Split(tt.args.code, tt.args.length); !reflect.DeepEqual(gotRes, tt.wantRes) {
+			if gotRes := Split(tt.args.code); !reflect.DeepEqual(gotRes, tt.wantRes) {
 				t.Errorf("Split() = %v, want %v", gotRes, tt.wantRes)
 			}
 		})
@@ -110,3 +122,43 @@ func TestTree(t *testing.T) {
 		})
 	}
 }
+
+func TestLength(t *testing.T) {
+	type args struct {
+		code string
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "test1",
+			args: args{
+				code: "A00001B00001C00001",
+			},
+			want: 6,
+		},
+		{
+			name: "test2",
+			args: args{
+				code: "C0001D0001E00001",
+			},
+			want: 5,
+		},
+		{
+			name: "test3",
+			args: args{
+				code: "A0001",
+			},
+			want: 5,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Length(tt.args.code); got != tt.want {
+				t.Errorf("length() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}