diff --git a/context/context.go b/context/context.go
index 1975863..45bcf50 100644
--- a/context/context.go
+++ b/context/context.go
@@ -13,6 +13,9 @@ type Context struct {
 	AppSecret      string
 	Token          string
 	EncodingAESKey string
+	PayMchID       string
+	PayNotifyURL   string
+	PayKey         string
 
 	Cache cache.Cache
 
diff --git a/pay/pay.go b/pay/pay.go
new file mode 100644
index 0000000..b9995d8
--- /dev/null
+++ b/pay/pay.go
@@ -0,0 +1,123 @@
+package pay
+
+import (
+	"errors"
+	"encoding/xml"
+	"fmt"	
+	"github.com/silenceper/wechat/context"
+	"github.com/silenceper/wechat/util"
+)
+
+var payGateway = "https://api.mch.weixin.qq.com/pay/unifiedorder"
+
+// Pay struct extends context
+type Pay struct {
+	*context.Context
+}
+
+// 传入的参数，用于生成 prepay_id 的必需参数
+// PayParams was NEEDED when request unifiedorder
+type PayParams struct {
+	TotalFee    string
+	CreateIP    string
+	Body        string
+	OutTradeNo  string
+	OpenID      string
+}
+
+// PayConfig 是传出用于 jsdk 用的参数
+type PayConfig struct {
+	Timestamp       int64
+	NonceStr        string
+	PrePayID        string
+	SignType        string
+	Sign            string
+}
+
+// payResult 是 unifie order 接口的返回
+type payResult struct {
+	ReturnCode      string `xml:"return_code"`
+	ReturnMsg       string `xml:"return_msg"`
+	AppID           string `xml:"appid,omitempty"`
+	MchID           string `xml:"mch_id,omitempty"`
+	NonceStr        string `xml:"nonce_str,omitempty"`
+	Sign            string `xml:"sign,omitempty"`
+	ResultCode      string `xml:"result_code,omitempty"`
+	TradeType       string `xml:"trade_type,omitempty"`
+	PrePayID        string `xml:"prepay_id,omitempty"`
+	CodeURL         string `xml:"code_url,omitempty"`
+	ErrCode         string `xml:"err_code,omitempty"`
+	ErrCodeDes      string `xml:"err_code_des,omitempty"`
+}
+
+//payRequest 接口请求参数
+type payRequest struct {
+	AppID           string `xml:"appid"`
+	MchID           string `xml:"mch_id"`
+	DeviceInfo      string `xml:"device_info,omitempty"`
+	NonceStr        string `xml:"nonce_str"`
+	Sign            string `xml:"sign"`
+	SignType        string `xml:"sign_type,omitempty"`
+	Body            string `xml:"body"`
+	Detail          string `xml:"detail,omitempty"`
+	Attach          string `xml:"attach,omitempty"` //附加数据
+	OutTradeNo      string `xml:"out_trade_no"` //商户订单号
+	FeeType         string `xml:"fee_type,omitempty"` //标价币种
+	TotalFee        string `xml:"total_fee"` //标价金额
+	SpbillCreateIp  string `xml:"spbill_create_ip"` //终端IP
+	TimeStart       string `xml:"time_start,omitempty"`  //交易起始时间
+	TimeExpire      string `xml:"time_expire,omitempty"`  //交易结束时间
+	GoodsTag        string `xml:"goods_tag,omitempty"`  //订单优惠标记
+	NotifyUrl       string `xml:"notify_url"` //通知地址	
+	TradeType       string `xml:"trade_type"` //交易类型
+	ProductId       string `xml:"product_id,omitempty"`  //商品ID
+	LimitPay        string `xml:"limit_pay,omitempty"` //
+	OpenID          string `xml:"openid,omitempty"` //用户标识
+	SceneInfo       string `xml:"scene_info,omitempty"` //场景信息	
+}
+
+// NewPay return an instance of Pay package
+func NewPay(ctx *context.Context) *Pay {
+	pay := Pay{Context: ctx}
+	return &pay
+}
+
+// PrePayId will request wechat merchant api and request for a pre payment order id
+func (pcf *Pay) PrePayId(p *PayParams) (prePayID string, err error) {
+	nonceStr := util.RandomStr(32)
+	tradeType := "JSAPI"
+	template := "appid=%s&body=%s&mch_id=%s&nonce_str=%s&notify_url=%s&openid=%s&out_trade_no=%s&spbill_create_ip=%s&total_fee=%s&trade_type=%s&key=%s"
+	str := fmt.Sprintf(template, pcf.AppID, p.Body, pcf.PayMchID, nonceStr, pcf.PayNotifyURL, p.OpenID, p.OutTradeNo, p.CreateIP, p.TotalFee, tradeType, pcf.PayKey)
+	sign := util.MD5Sum(str)
+	request := payRequest{
+		AppID: pcf.AppID,
+		MchID: pcf.PayMchID,
+		NonceStr: nonceStr,
+		Sign: sign,
+		Body: p.Body,
+		OutTradeNo: p.OutTradeNo,
+		TotalFee: p.TotalFee,
+		SpbillCreateIp: p.CreateIP,
+		NotifyUrl: pcf.PayNotifyURL,		
+		TradeType: tradeType,
+		OpenID: p.OpenID,
+	}
+	rawRet, err := util.PostXML(payGateway, request)
+	if err != nil {
+		return "", errors.New(err.Error() + " parameters : " + str)
+	}
+	payRet := payResult{}
+	err = xml.Unmarshal(rawRet, &payRet)
+	if err != nil {
+		return "", errors.New(err.Error())
+	}
+	if payRet.ReturnCode == "SUCCESS" {
+		//pay success
+		if payRet.ResultCode == "SUCCESS" {
+			return payRet.PrePayID, nil
+		}
+		return "", errors.New(payRet.ErrCode + payRet.ErrCodeDes)
+	} else {
+		return "", errors.New("[msg : xmlUnmarshalError] [rawReturn : " + string(rawRet) + "] [params : " + str + "] [sign : " + sign + "]")		
+	}
+}
\ No newline at end of file
diff --git a/util/crypto.go b/util/crypto.go
index 1ec7a4f..98e2b4e 100644
--- a/util/crypto.go
+++ b/util/crypto.go
@@ -1,9 +1,13 @@
 package util
 
 import (
+	"bytes"
+	"bufio"
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/md5"
 	"encoding/base64"
+	"encoding/hex"
 	"fmt"
 )
 
@@ -181,3 +185,15 @@ func decodeNetworkByteOrder(orderBytes []byte) (n uint32) {
 		uint32(orderBytes[2])<<8 |
 		uint32(orderBytes[3])
 }
+
+// 计算 32 位长度的 MD5 sum
+func MD5Sum(txt string) (sum string) {
+	h := md5.New()
+	buf := bufio.NewWriterSize(h, 128)
+	buf.WriteString(txt)
+	buf.Flush()
+	sign := make([]byte, hex.EncodedLen(h.Size()))
+	hex.Encode(sign, h.Sum(nil))
+	sum = string(bytes.ToUpper(sign))
+	return
+}
diff --git a/util/http.go b/util/http.go
index ca98ae7..6881052 100644
--- a/util/http.go
+++ b/util/http.go
@@ -3,6 +3,7 @@ package util
 import (
 	"bytes"
 	"encoding/json"
+	"encoding/xml"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -120,3 +121,23 @@ func PostMultipartForm(fields []MultipartFormField, uri string) (respBody []byte
 	respBody, err = ioutil.ReadAll(resp.Body)
 	return
 }
+
+//PostXML perform a HTTP/POST request with XML body
+func PostXML(uri string, obj interface{}) ([]byte, error) {
+	xmlData, err := xml.Marshal(obj)
+	if err != nil {
+		return nil, err
+	}
+
+	body := bytes.NewBuffer(xmlData)
+	response, err := http.Post(uri, "application/xml;charset=utf-8", body)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("http code error : uri=%v , statusCode=%v", uri, response.StatusCode)
+	}
+	return ioutil.ReadAll(response.Body)
+}
diff --git a/wechat b/wechat
new file mode 120000
index 0000000..4e7c289
--- /dev/null
+++ b/wechat
@@ -0,0 +1 @@
+wechat
\ No newline at end of file
diff --git a/wechat.go b/wechat.go
index e48de19..02e3a34 100644
--- a/wechat.go
+++ b/wechat.go
@@ -13,6 +13,7 @@ import (
 	"github.com/silenceper/wechat/server"
 	"github.com/silenceper/wechat/template"
 	"github.com/silenceper/wechat/user"
+	"github.com/silenceper/wechat/pay"
 )
 
 // Wechat struct
@@ -26,6 +27,9 @@ type Config struct {
 	AppSecret      string
 	Token          string
 	EncodingAESKey string
+	PayMchID       string  //支付 - 商户 ID
+	PayNotifyURL   string  //支付 - 接受微信支付结果通知的接口地址
+	PayKey         string  //支付 - 商户后台设置的支付 key
 	Cache          cache.Cache
 }
 
@@ -41,6 +45,9 @@ func copyConfigToContext(cfg *Config, context *context.Context) {
 	context.AppSecret = cfg.AppSecret
 	context.Token = cfg.Token
 	context.EncodingAESKey = cfg.EncodingAESKey
+	context.PayMchID = cfg.PayMchID
+	context.PayKey = cfg.PayKey
+	context.PayNotifyURL = cfg.PayNotifyURL
 	context.Cache = cfg.Cache
 	context.SetAccessTokenLock(new(sync.RWMutex))
 	context.SetJsAPITicketLock(new(sync.RWMutex))
@@ -87,3 +94,8 @@ func (wc *Wechat) GetUser() *user.User {
 func (wc *Wechat) GetTemplate() *template.Template {
 	return template.NewTemplate(wc.Context)
 }
+
+// GetPay 返回支付消息的实例
+func (wc *Wechat) GetPay() *pay.Pay {
+	return pay.NewPay(wc.Context)
+}
\ No newline at end of file