diff --git a/cmd/perfmon.go b/cmd/perfmon.go
index 095a771..97cf929 100644
--- a/cmd/perfmon.go
+++ b/cmd/perfmon.go
@@ -89,7 +89,7 @@ var (
 
 func init() {
 	rootCmd.AddCommand(perfmonCmd)
-	perfmonCmd.Flags().StringVarP(&serial, "serial", "s", "", "device serial")
+	perfmonCmd.Flags().StringVarP(&serial, "serial", "s", "", "device serial (default first device)")
 	perfmonCmd.Flags().IntVarP(&pid, "pid", "d", -1, "get PID data")
 	perfmonCmd.Flags().StringVarP(&packageName, "package", "p", "", "app package name")
 	perfmonCmd.Flags().BoolVar(&perfOptions.SystemCPU, "sys-cpu", false, "get system cpu data")
@@ -102,7 +102,7 @@ func init() {
 	//perfmonCmd.Flags().BoolVar(&, "proc-network", false, "get process network data")
 	perfmonCmd.Flags().BoolVar(&perfOptions.ProcCPU, "proc-cpu", false, "get process cpu data")
 	perfmonCmd.Flags().BoolVar(&perfOptions.ProcMem, "proc-mem", false, "get process mem data")
-	perfmonCmd.Flags().IntVarP(&refreshTime, "refresh", "r", 1000, "data refresh time(millisecond)")
+	perfmonCmd.Flags().IntVarP(&refreshTime, "refresh", "r", 1000, "data refresh time (millisecond)")
 	perfmonCmd.Flags().BoolVarP(&isFormat, "format", "f", false, "convert to JSON string and format")
 	perfmonCmd.Flags().BoolVarP(&isJson, "json", "j", false, "convert to JSON string")
 }
diff --git a/src/perfmonUtil/process.go b/src/perfmonUtil/process.go
index d647d2e..5c76a59 100644
--- a/src/perfmonUtil/process.go
+++ b/src/perfmonUtil/process.go
@@ -376,7 +376,7 @@ func GetProcessInfo(client *adb.Device, pid string, packageName string, perfOpti
 		if processInfo == nil {
 			processInfo = &entity.ProcessInfo{}
 		}
-		var fps = 0
+		fps := 0
 
 		fps, err = getProcessFPSBySurfaceFlinger(client, packageName)
 
@@ -466,7 +466,7 @@ func getProcessFPSBySurfaceFlinger(client *adb.Device, pkg string) (result int,
 		break
 	}
 	if activity == "" {
-		return 0, errors.New(fmt.Sprintf("not find app %s activity", pkg))
+		return 0, errors.New(fmt.Sprintf("could not find app %s activity", pkg))
 	}
 	//var r = strings.NewReplacer("[", "", "")
 	activity = strings.Replace(activity, "[", "", 1)