diff --git a/client.go b/client.go
index bd50cd2..80e780d 100644
--- a/client.go
+++ b/client.go
@@ -360,7 +360,11 @@ func (c *Client) WebWxUploadMediaByChunk(file *os.File, request *BaseRequest, in
 	path.RawQuery = params.Encode()
 
 	cookies := c.Jar().Cookies(path)
-	webWxDataTicket := getWebWxDataTicket(cookies)
+
+	webWxDataTicket, err := getWebWxDataTicket(cookies)
+	if err != nil {
+		return nil, err
+	}
 
 	uploadMediaRequest := map[string]interface{}{
 		"UploadType":    2,
@@ -593,13 +597,18 @@ func (c *Client) WebWxGetVideo(msg *Message, info *LoginInfo) (*http.Response, e
 // WebWxGetMedia 获取文件消息的文件响应
 func (c *Client) WebWxGetMedia(msg *Message, info *LoginInfo) (*http.Response, error) {
 	path, _ := url.Parse(c.Domain.FileHost() + webwxgetmedia)
+	cookies := c.Jar().Cookies(path)
+	webWxDataTicket, err := getWebWxDataTicket(cookies)
+	if err != nil {
+		return nil, err
+	}
 	params := url.Values{}
 	params.Add("sender", msg.FromUserName)
 	params.Add("mediaid", msg.MediaId)
 	params.Add("encryfilename", msg.EncryFileName)
 	params.Add("fromuser", strconv.FormatInt(info.WxUin, 10))
 	params.Add("pass_ticket", info.PassTicket)
-	params.Add("webwx_data_ticket", getWebWxDataTicket(c.Jar().Cookies(path)))
+	params.Add("webwx_data_ticket", webWxDataTicket)
 	path.RawQuery = params.Encode()
 	req, _ := http.NewRequest(http.MethodGet, path.String(), nil)
 	req.Header.Add("Referer", c.Domain.BaseHost()+"/")
diff --git a/jar.go b/cookiejar.go
similarity index 68%
rename from jar.go
rename to cookiejar.go
index fd32cfb..434e1e7 100644
--- a/jar.go
+++ b/cookiejar.go
@@ -9,6 +9,7 @@ import (
 )
 
 // Jar is a struct which as same as cookiejar.Jar
+// cookiejar.Jar's fields are private, so we can't use it directly
 type Jar struct {
 	PsList cookiejar.PublicSuffixList
 
@@ -57,3 +58,24 @@ type entry struct {
 	// equal Creation time. This simplifies testing.
 	seqNum uint64
 }
+
+// CookieGroup is a group of cookies
+type CookieGroup []*http.Cookie
+
+func (c CookieGroup) GetByName(cookieName string) (cookie *http.Cookie, exist bool) {
+	for _, cookie := range c {
+		if cookie.Name == cookieName {
+			return cookie, true
+		}
+	}
+	return nil, false
+}
+
+func getWebWxDataTicket(cookies []*http.Cookie) (string, error) {
+	cookieGroup := CookieGroup(cookies)
+	cookie, exist := cookieGroup.GetByName("webwx_data_ticket")
+	if !exist {
+		return "", ErrWebWxDataTicketNotFound
+	}
+	return cookie.Value, nil
+}
diff --git a/errors.go b/errors.go
index 4c2b378..036516a 100644
--- a/errors.go
+++ b/errors.go
@@ -32,6 +32,9 @@ var (
 
 	// ErrLoginTimeout define login timeout error
 	ErrLoginTimeout = errors.New("login timeout")
+
+	// ErrWebWxDataTicketNotFound define webwx_data_ticket not found error
+	ErrWebWxDataTicketNotFound = errors.New("webwx_data_ticket not found")
 )
 
 // Error impl error interface
diff --git a/parser.go b/parser.go
index 80ed563..d3f4480 100644
--- a/parser.go
+++ b/parser.go
@@ -38,15 +38,6 @@ func GetRandomDeviceId() string {
 	return builder.String()
 }
 
-func getWebWxDataTicket(cookies []*http.Cookie) string {
-	for _, cookie := range cookies {
-		if cookie.Name == "webwx_data_ticket" {
-			return cookie.Value
-		}
-	}
-	return ""
-}
-
 // GetFileContentType 获取文件上传的类型
 func GetFileContentType(file multipart.File) (string, error) {
 	data := make([]byte, 512)