diff --git a/reader/cloudwatch/cloudwatch.go b/reader/cloudwatch/cloudwatch.go
index d38945293..95a5b4cbe 100644
--- a/reader/cloudwatch/cloudwatch.go
+++ b/reader/cloudwatch/cloudwatch.go
@@ -430,7 +430,7 @@ func formatKey(metricName string, statistic string) string {
 }
 
 func snakeCase(s string) string {
-	s = models.PandoraKey(s)
+	s, _ = models.PandoraKey(s)
 	s = strings.Replace(s, "__", "_", -1)
 	return s
 }
diff --git a/utils/models/utils.go b/utils/models/utils.go
index 4729443e0..a1bbd4d26 100644
--- a/utils/models/utils.go
+++ b/utils/models/utils.go
@@ -752,31 +752,74 @@ func GetMapList(data string) map[string]string {
 	return ret
 }
 
-func PandoraKey(key string) string {
-	var nk string
-	for _, c := range key {
+// 判断时只有数字和字母为合法字符，规则：
+// 1. 首字符为数字时，增加首字符 "K"
+// 2. 首字符为非法字符时，去掉首字符（例如，如果字符串全为非法字符，则转换后为空）
+// 3. 非首字符并且为非法字符时，使用 "_" 替代非法字符
+func PandoraKey(key string) (string, bool) {
+	// check
+	valid := true
+	size := 0
+	for idx, c := range key {
 		if c >= '0' && c <= '9' {
-			if len(nk) == 0 {
-				nk = "K"
+			size++
+			if idx == 0 {
+				size++
+				valid = false
 			}
-			nk = nk + string(c)
-		} else if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') {
-			nk = nk + string(c)
-		} else if len(nk) > 0 {
-			nk = nk + "_"
+			continue
+		}
+		if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') {
+			size++
+			continue
+		}
+
+		if idx > 0 && size > 0 {
+			size++
 		}
+		valid = false
 	}
-	return nk
+	if valid {
+		return key, true
+	}
+
+	if size <= 0 {
+		return "", false
+	}
+
+	// set
+	bytes := make([]byte, size)
+	bp := 0
+	for idx, c := range key {
+		if c >= '0' && c <= '9' {
+			if idx == 0 {
+				bp += copy(bytes, "K")
+			}
+			bp += copy(bytes[bp:], string(c))
+			continue
+		}
+		if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') {
+			bp += copy(bytes[bp:], string(c))
+			continue
+		}
+
+		if idx > 0 {
+			bp += copy(bytes[bp:], "_")
+		}
+	}
+	return string(bytes), false
 }
 
 func DeepConvertKey(data map[string]interface{}) map[string]interface{} {
-	newData := make(map[string]interface{})
 	for k, v := range data {
-		nk := PandoraKey(k)
+		nk, valid := PandoraKey(k)
 		if nv, ok := v.(map[string]interface{}); ok {
 			v = DeepConvertKey(nv)
 		}
-		newData[nk] = v
+		if !valid {
+			delete(data, k)
+			data[nk] = v
+		}
 	}
-	return newData
+	return data
 }
diff --git a/utils/models/utils_test.go b/utils/models/utils_test.go
index bb7f70039..b22e2b321 100644
--- a/utils/models/utils_test.go
+++ b/utils/models/utils_test.go
@@ -618,9 +618,44 @@ func TestPickMapValue(t *testing.T) {
 func TestPandoraKey(t *testing.T) {
 	testKeys := []string{"@timestamp", ".dot", "percent%100", "^^^^^^^^^^", "timestamp"}
 	expectKeys := []string{"timestamp", "dot", "percent_100", "", "timestamp"}
+	expectValid := []bool{false, false, false, false, true}
 	for idx, key := range testKeys {
-		actual := PandoraKey(key)
+		actual, valid := PandoraKey(key)
 		assert.Equal(t, expectKeys[idx], actual)
+		assert.Equal(t, expectValid[idx], valid)
+	}
+}
+
+func BenchmarkPandoraKey(b *testing.B) {
+	b.ReportAllocs()
+	testKeys := []string{"@timestamp", ".dot", "percent%100", "^^^^^^^^^^", "timestamp", "aaa"}
+	for i := 0; i < b.N; i++ {
+		for _, key := range testKeys {
+			PandoraKey(key)
+		}
+	}
+}
+
+func BenchmarkDeepConvertKey(b *testing.B) {
+	b.ReportAllocs()
+	testDatas := []map[string]interface{}{
+		{
+			"@timestamp": "2018-07-18T10:17:36.549054846+08:00",
+			//"timestamp":  "2018-07-19T10:17:36.549054846+08:00",
+		},
+		{
+			".dot": map[string]interface{}{".dot2": "dot"},
+		},
+		{
+			"dot":         map[string]interface{}{".dot2": "dot"},
+			"percent%100": 100,
+			"^^^^^^^^^^":  "mytest",
+		},
+	}
+	for i := 0; i < b.N; i++ {
+		for _, data := range testDatas {
+			DeepConvertKey(data)
+		}
 	}
 }
 
@@ -631,10 +666,10 @@ func TestDeepConvertKey(t *testing.T) {
 			//"timestamp":  "2018-07-19T10:17:36.549054846+08:00",
 		},
 		{
-			".dot": "dot",
+			".dot": map[string]interface{}{".dot2": "dot"},
 		},
 		{
-			"dot":         "dot",
+			"dot":         map[string]interface{}{".dot2": "dot"},
 			"percent%100": 100,
 			"^^^^^^^^^^":  "mytest",
 		},
@@ -644,10 +679,10 @@ func TestDeepConvertKey(t *testing.T) {
 			"timestamp": "2018-07-18T10:17:36.549054846+08:00",
 		},
 		{
-			"dot": "dot",
+			"dot": map[string]interface{}{"dot2": "dot"},
 		},
 		{
-			"dot":         "dot",
+			"dot":         map[string]interface{}{"dot2": "dot"},
 			"percent_100": 100,
 			"":            "mytest",
 		},