diff --git a/bot.go b/bot.go
index 98a2856..4ac7ac2 100644
--- a/bot.go
+++ b/bot.go
@@ -139,7 +139,7 @@ func (b *Bot) Login() error {
 				b.ScanCallBack(resp.Raw)
 			}
 		case StatusTimeout:
-			return errors.New("login time out")
+			return ErrLoginTimeout
 		case StatusWait:
 			continue
 		}
@@ -307,7 +307,7 @@ func (b *Bot) MessageOnError(h func(err error)) {
 // DumpHotReloadStorage 写入HotReloadStorage
 func (b *Bot) DumpHotReloadStorage() error {
 	if b.HotReloadStorage == nil {
-		return errors.New("HotReloadStorage can be nil")
+		return errors.New("HotReloadStorage can not be nil")
 	}
 	cookies := b.Caller.Client.GetCookieMap()
 	item := HotReloadStorageItem{
diff --git a/caller.go b/caller.go
index d469877..4019dea 100644
--- a/caller.go
+++ b/caller.go
@@ -84,8 +84,8 @@ func (c *Caller) GetLoginInfo(body []byte) (*LoginInfo, error) {
 	resp, err := c.Client.GetLoginInfo(path.String())
 	if err != nil {
 		uErr, ok := err.(*url.Error)
-		if ok && (uErr.Err.Error() == missLocationHeader.Error()) {
-			return nil, loginForbiddenError
+		if ok && (uErr.Err.Error() == ErrMissLocationHeader.Error()) {
+			return nil, ErrLoginForbiddenError
 		}
 		return nil, err
 	}
diff --git a/global.go b/global.go
index aecf685..5851a93 100644
--- a/global.go
+++ b/global.go
@@ -116,9 +116,10 @@ const (
 
 // errors
 var (
-	noSuchUserFoundError = errors.New("no such user found")
-	missLocationHeader   = errors.New("301 response missing Location header")
-	loginForbiddenError  = errors.New("login forbidden")
+	ErrNoSuchUserFoundError = errors.New("no such user found")
+	ErrMissLocationHeader   = errors.New("301 response missing Location header")
+	ErrLoginForbiddenError  = errors.New("login forbidden")
+	ErrLoginTimeout         = errors.New("login timeout")
 )
 
 // ALL 跟search函数搭配
diff --git a/items.go b/items.go
index 6e7d0c5..6b9d9f0 100644
--- a/items.go
+++ b/items.go
@@ -20,6 +20,28 @@ type LoginInfo struct {
 	PassTicket  string `xml:"pass_ticket"`
 }
 
+// errors
+const (
+	errParamError         = "param error"
+	errTicketError        = "ticket error"
+	errLoginEnvError      = "login env error"
+	errLoginFailedWarn    = "failed login warn"
+	errLoginFailedCheck   = "failed login check"
+	errCookieInvalidError = "cookie invalid error"
+	errOptTooOften        = "opt too often"
+)
+
+var (
+	ErrParamError         = errors.New(errParamError)
+	ErrTicketError        = errors.New(errTicketError)
+	ErrLoginEnvError      = errors.New(errLoginEnvError)
+	ErrLoginFailedWarn    = errors.New(errLoginFailedWarn)
+	ErrLoginFailedCheck   = errors.New(errLoginFailedCheck)
+	ErrCookieInvalidError = errors.New(errCookieInvalidError)
+	ErrOptTooOften        = errors.New(errOptTooOften)
+	ErrBaseResponseError  error
+)
+
 func (l LoginInfo) Ok() bool {
 	return l.Ret == 0
 }
@@ -57,21 +79,22 @@ func getResponseErrorWithRetCode(code int) error {
 	case 0:
 		return nil
 	case 1:
-		return errors.New("param error")
+		return ErrParamError
 	case -14:
-		return errors.New("ticket error")
+		return ErrTicketError
 	case 1100:
-		return errors.New("not login warn")
+		return ErrLoginFailedWarn
 	case 1101:
-		return errors.New("not login check")
+		return ErrLoginFailedCheck
 	case 1102:
-		return errors.New("cookie invalid error")
+		return ErrCookieInvalidError
 	case 1203:
-		return errors.New("login env error")
+		return ErrLoginEnvError
 	case 1205:
-		return errors.New("opt too often")
+		return ErrOptTooOften
 	default:
-		return fmt.Errorf("base response ret code %d", code)
+		ErrBaseResponseError = fmt.Errorf("base response ret code %d", code)
+		return ErrBaseResponseError
 	}
 }
 
@@ -147,19 +170,19 @@ func (s *SyncCheckResponse) Error() string {
 	case "0":
 		return ""
 	case "1":
-		return "param error"
+		return errParamError
 	case "-14":
-		return "ticker error"
+		return errTicketError
 	case "1100":
-		return "not login warn"
+		return errLoginFailedWarn
 	case "1101":
-		return "not login check"
+		return errLoginFailedCheck
 	case "1102":
-		return "cookie invalid error"
+		return errCookieInvalidError
 	case "1203":
-		return "login env error"
+		return errLoginEnvError
 	case "1205":
-		return "opt too often"
+		return errOptTooOften
 	default:
 		return fmt.Sprintf("sync check response error code %s", s.RetCode)
 	}
diff --git a/message.go b/message.go
index 35fb4b5..76c4b2c 100644
--- a/message.go
+++ b/message.go
@@ -80,7 +80,7 @@ func (m *Message) SenderInGroup() (*User, error) {
 	}
 	users := group.MemberList.SearchByUserName(1, m.senderInGroupUserName)
 	if users == nil {
-		return nil, noSuchUserFoundError
+		return nil, ErrNoSuchUserFoundError
 	}
 	users.init(m.Bot.self)
 	return users.First(), nil
@@ -94,14 +94,14 @@ func (m *Message) Receiver() (*User, error) {
 		} else {
 			users := sender.MemberList.SearchByUserName(1, m.ToUserName)
 			if users == nil {
-				return nil, noSuchUserFoundError
+				return nil, ErrNoSuchUserFoundError
 			}
 			return users.First(), nil
 		}
 	} else {
 		users := m.Bot.self.MemberList.SearchByUserName(1, m.ToUserName)
 		if users == nil {
-			return nil, noSuchUserFoundError
+			return nil, ErrNoSuchUserFoundError
 		}
 		return users.First(), nil
 	}