diff --git a/metric/common.go b/metric/common.go
index 5ca63e6..996b2d1 100644
--- a/metric/common.go
+++ b/metric/common.go
@@ -9,6 +9,7 @@ import (
 	"math"
 	"os"
 	"path"
+	"sort"
 	"strings"
 	"sync/atomic"
 
@@ -67,11 +68,26 @@ func NewMetric(mt MetricType, name string, help string, constLabels map[string]s
 		return MetricWriterNil
 	}
 
-	hash := md5.New()
-	hash.Write([]byte(name))
+	var disorder []struct {
+		k string
+		v string
+	}
 	for k, v := range constLabels {
-		hash.Write([]byte(k))
-		hash.Write([]byte(v))
+		disorder = append(disorder, struct {
+			k string
+			v string
+		}{k: strings.ToLower(k), v: strings.ToLower(v)})
+	}
+
+	sort.Slice(disorder, func(i, j int) bool {
+		return disorder[i].k < disorder[j].k
+	})
+
+	hash := md5.New()
+	hash.Write([]byte(strings.ToLower(name)))
+	for _, d := range disorder {
+		hash.Write([]byte(d.k))
+		hash.Write([]byte(d.v))
 	}
 
 	key := hex.EncodeToString(hash.Sum(nil))[:metric_key_size]