diff --git a/example/web_example.js b/example/web_example.js
index 1c953ee..88bf066 100644
--- a/example/web_example.js
+++ b/example/web_example.js
@@ -7,7 +7,10 @@ var ccap = require('../')({
 	height:50,
 	offset:30,
 	quality:100,
-  fontsize:40
+  fontsize:40,
+  text_len: 4, // 长度
+  str_ary: ['1','2','3','4','5','6','7','9','A','C','D','E','F','G','H',
+	'I','J','K','L','M','N','R','S','T','U','W','X','Y','Z'], // 自定义字符组，去掉一些容易搞错的字符如0 O 8 B等
 });
 
 http.createServer(function (request, response) {
diff --git a/lib/gen.js b/lib/gen.js
index 4b3a2c8..a7e16f5 100644
--- a/lib/gen.js
+++ b/lib/gen.js
@@ -1,14 +1,12 @@
-var str_ary = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H',
-'I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
+
 //定义随机数组
 
-var gen_fuc = function(){
-	var str_num = 6,
-		r_num = str_ary.length,
+var gen_fuc = function(options){
+	 var r_num = options.str_ary.length,
 		text = '';
-	for(var i=0;i<str_num;i++){
+	for(var i=0;i<options.str_num;i++){
 		var pos = Math.floor(Math.random()*r_num)
-		text += str_ary[pos];//生成随机数
+		text += options.str_ary[pos];//生成随机数
 	}
 	return text;
 }
diff --git a/lib/hcap.js b/lib/hcap.js
index bfe4cab..0c72c4c 100644
--- a/lib/hcap.js
+++ b/lib/hcap.js
@@ -35,8 +35,6 @@ var pathCluster =  cluster.isWorker ? String(cluster.worker.id) : '0';
 
 var img_path = path.join(rootPath, pathCluster);
 var pid = process.pid;
-
-
 	
 var isjpeg = (os.platform() == 'linux')? 1 : 0;//判断是否启用jpeg,如果是为win32则只能使用bmp
 
@@ -61,6 +59,9 @@ var CAP = function(args){
 	this.buf = [];//缓存数组
 	this.text_buf = [];//定义字符串内容数组
 
+	this.str_ary = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H',
+	'I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
+
 	this._init(args);//构造函数
 
 	this._create = this.generate ? this._custom_create : this._default_create;
@@ -82,9 +83,11 @@ CAP.prototype._init = function(args){
 		this.width = obj.width || this.width;
 		this.height = obj.height || this.height;
 		this.offset = obj.offset || this.offset;
-	    this.quality = obj.quality || this.quality;
+	  this.quality = obj.quality || this.quality;
 		this.generate = obj.generate || null;
 		this.fontsize = obj.fontsize || this.fontsize;
+		this.str_ary = obj.str_ary || this.str_ary;
+		this.text_len = obj.text_len || this._text_len;
 		return;
 	}
 	//如果只传递了宽，高，间隔则替换默认值
@@ -125,9 +128,9 @@ CAP.prototype._call_create = function(text,len,j){//调用C++的CIMG库的create
 }
 
 CAP.prototype._default_create = function(){//默认方式创建
-	
+	var str_num = this.text_len || this._text_len;
 	for(var i=0;i<this._cache_num;i++){			
-		this._call_create(this._default_generate(), this._text_len, i)
+		this._call_create(this._default_generate({str_ary: this.str_ary, str_num: str_num}), this._text_len, i)
 	}
 
 	return this;
diff --git a/test/main_test.js b/test/main_test.js
index 13f36c7..a60a916 100644
--- a/test/main_test.js
+++ b/test/main_test.js
@@ -105,11 +105,23 @@ assert.equal(captcha8.timerIsRunning(),0)
 captcha8.setTimeout()
 assert.equal(captcha8.timerIsRunning(),1)
 
-console.log('ccap all test done!')
-
-
+var captcha9 = ccap({
+	width:200,
+	height:50,
+	offset:30,
+	quality:100,
+  fontsize:40,
+  text_len: 4, // 长度
+  str_ary: ['1','2','3','4','5','6','7','9','A','C','D','E','F','G','H',
+	'I','J','K','L','M','N','R','S','T','U','W','X','Y','Z'], // 自定义字符组，去掉一些容易搞错的字符如0 O 8 B等
+});
+var ary = captcha9.get();
 
+assert.equal(/\w/.test(ary[0]),true)
+assert.equal(ary[0].length,4)
+assert.equal(Buffer.isBuffer(ary[1]), true)
 
+console.log('ccap all test done!')
 
 process.exit(0)