diff --git a/README.md b/README.md
index 74427b4..f4c616b 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,44 @@
 # Simple Log
 
 A very simple log system(golang).
+
+## Install
+
+```bash
+go get github.com/lion187chen/simplelog
+```
+
+## Demo
+
+```go
+package main
+
+import (
+    "time"
+
+    "github.com/lion187chen/simplelog"
+)
+
+func CreateLog(file string, LogLevel simplelog.LogLevel) *simplelog.SimpleLog {
+    switch file {
+    case "":
+        return new(simplelog.SimpleLog).InitStd(LogLevel, simplelog.Ltime|simplelog.Lfile|simplelog.Llevel)
+    default:
+        return new(simplelog.SimpleLog).InitRotating(file, 1024*10, 10, LogLevel)
+    }
+}
+
+func main() {
+    log := CreateLog("./log/MS.log", simplelog.LevelInfo)
+    for i := 0; i < 10000000; i++ {
+        log.Trace("hello world")
+        log.Debug("hello world")
+        log.Info("hello world")
+        log.Warn("hello world")
+        log.Error("hello world")
+        log.Fatal("hello world")
+        time.Sleep(8 * time.Millisecond)
+    }
+}
+
+```
diff --git a/demo/main.go b/demo/main.go
index b101914..546990f 100644
--- a/demo/main.go
+++ b/demo/main.go
@@ -6,12 +6,24 @@ import (
 	"github.com/lion187chen/simplelog"
 )
 
-var sl *simplelog.SimpleLog
+func CreateLog(file string, LogLevel simplelog.LogLevel) *simplelog.SimpleLog {
+	switch file {
+	case "":
+		return new(simplelog.SimpleLog).InitStd(LogLevel, simplelog.Ltime|simplelog.Lfile|simplelog.Llevel)
+	default:
+		return new(simplelog.SimpleLog).InitRotating(file, 1024*10, 10, LogLevel)
+	}
+}
 
 func main() {
-	sl = new(simplelog.SimpleLog).InitRotating("./log/MS.log", 1024*10, 10, simplelog.LevelTrace)
+	log := CreateLog("./log/MS.log", simplelog.LevelInfo)
 	for i := 0; i < 10000000; i++ {
-		sl.Debug("hello world")
+		log.Trace("hello world")
+		log.Debug("hello world")
+		log.Info("hello world")
+		log.Warn("hello world")
+		log.Error("hello world")
+		log.Fatal("hello world")
 		time.Sleep(8 * time.Millisecond)
 	}
 }
diff --git a/simplelog.go b/simplelog.go
index 3a19a3b..1684b4c 100644
--- a/simplelog.go
+++ b/simplelog.go
@@ -28,9 +28,11 @@ import (
 	"time"
 )
 
+type LogLevel int
+
 // log level, from low to high, more higher means more serious
 const (
-	LevelTrace = iota
+	LevelTrace LogLevel = iota
 	LevelDebug
 	LevelInfo
 	LevelWarn
@@ -91,8 +93,8 @@ type SimpleLog struct {
 //	log.Lfile
 //	log.Llevel
 //	的组合
-func (l *SimpleLog) Init(handler StreamHandler, level, flag int) *SimpleLog {
-	l.level.Set(level)
+func (l *SimpleLog) Init(handler StreamHandler, level LogLevel, flag int) *SimpleLog {
+	l.level.Set(int(level))
 	l.handler = handler
 
 	l.flag = flag
@@ -103,7 +105,7 @@ func (l *SimpleLog) Init(handler StreamHandler, level, flag int) *SimpleLog {
 	return l
 }
 
-func (l *SimpleLog) InitStd(level, flag int) *SimpleLog {
+func (l *SimpleLog) InitStd(level LogLevel, flag int) *SimpleLog {
 	handler, e := NewStreamHandle(os.Stdout)
 	if e != nil {
 		panic(e)
@@ -112,7 +114,7 @@ func (l *SimpleLog) InitStd(level, flag int) *SimpleLog {
 	return l.Init(handler, level, flag)
 }
 
-func (l *SimpleLog) InitFile(name string, level, flag int) *SimpleLog {
+func (l *SimpleLog) InitFile(name string, level LogLevel, flag int) *SimpleLog {
 	handler, e := new(FileHandler).InitFile(name)
 	if e != nil {
 		panic(e)
@@ -121,7 +123,7 @@ func (l *SimpleLog) InitFile(name string, level, flag int) *SimpleLog {
 	return l.Init(handler, level, flag)
 }
 
-func (l *SimpleLog) InitRotating(name string, maxBytes, backupCount, level int) *SimpleLog {
+func (l *SimpleLog) InitRotating(name string, maxBytes, backupCount int, level LogLevel) *SimpleLog {
 	handler, e := new(RotatingFileHandler).InitRotating(name, maxBytes, backupCount)
 	if e != nil {
 		panic(e)
@@ -130,7 +132,7 @@ func (l *SimpleLog) InitRotating(name string, maxBytes, backupCount, level int)
 	return l.Init(handler, level, Ltime|Lfile|Llevel)
 }
 
-func (l *SimpleLog) InitTimedRotating(name string, when int8, interval, level int) *SimpleLog {
+func (l *SimpleLog) InitTimedRotating(name string, when int8, interval int, level LogLevel) *SimpleLog {
 	handler, e := new(TimedRotatingFileHandler).InitTimedRotating(name, when, interval)
 	if e != nil {
 		panic(e)
@@ -172,8 +174,8 @@ func (l *SimpleLog) Close() {
 }
 
 // set log level, any log level less than it will not log
-func (l *SimpleLog) SetLevel(level int) {
-	l.level.Set(level)
+func (l *SimpleLog) SetLevel(level LogLevel) {
+	l.level.Set(int(level))
 }
 
 // name can be in ["trace", "debug", "info", "warn", "error", "fatal"]
@@ -208,13 +210,13 @@ func (l *SimpleLog) SetHandler(h StreamHandler) {
 	l.hMutex.Unlock()
 }
 
-func (l *SimpleLog) Output(callDepth int, level int, format string, v ...interface{}) {
+func (l *SimpleLog) Output(callDepth int, level LogLevel, format string, v ...interface{}) {
 	if l.closed.Get() == 1 {
 		// closed
 		return
 	}
 
-	if l.level.Get() > level {
+	if l.level.Get() > int(level) {
 		// higher level can be logged
 		return
 	}