diff --git a/session/sess_cookie.go b/session/sess_cookie.go
index 7962be18..ddf1a902 100644
--- a/session/sess_cookie.go
+++ b/session/sess_cookie.go
@@ -11,12 +11,15 @@ import (
 
 var cookiepder = &CookieProvider{}
 
+// Cookie SessionStore
 type CookieSessionStore struct {
 	sid    string
-	values map[interface{}]interface{} //session data
+	values map[interface{}]interface{} // session data
 	lock   sync.RWMutex
 }
 
+// Set value to cookie session.
+// the value are encoded as gob with hash block string.
 func (st *CookieSessionStore) Set(key, value interface{}) error {
 	st.lock.Lock()
 	defer st.lock.Unlock()
@@ -24,6 +27,7 @@ func (st *CookieSessionStore) Set(key, value interface{}) error {
 	return nil
 }
 
+// Get value from cookie session
 func (st *CookieSessionStore) Get(key interface{}) interface{} {
 	st.lock.RLock()
 	defer st.lock.RUnlock()
@@ -35,6 +39,7 @@ func (st *CookieSessionStore) Get(key interface{}) interface{} {
 	return nil
 }
 
+// Delete value in cookie session
 func (st *CookieSessionStore) Delete(key interface{}) error {
 	st.lock.Lock()
 	defer st.lock.Unlock()
@@ -42,6 +47,7 @@ func (st *CookieSessionStore) Delete(key interface{}) error {
 	return nil
 }
 
+// Clean all values in cookie session
 func (st *CookieSessionStore) Flush() error {
 	st.lock.Lock()
 	defer st.lock.Unlock()
@@ -49,10 +55,12 @@ func (st *CookieSessionStore) Flush() error {
 	return nil
 }
 
+// Return id of this cookie session
 func (st *CookieSessionStore) SessionID() string {
 	return st.sid
 }
 
+// Write cookie session to http response cookie
 func (st *CookieSessionStore) SessionRelease(w http.ResponseWriter) {
 	str, err := encodeCookie(cookiepder.block,
 		cookiepder.config.SecurityKey,
@@ -79,12 +87,21 @@ type cookieConfig struct {
 	Maxage       int    `json:"maxage"`
 }
 
+// Cookie session provider
 type CookieProvider struct {
 	maxlifetime int64
 	config      *cookieConfig
 	block       cipher.Block
 }
 
+// Init cookie session provider with max lifetime and config json.
+// maxlifetime is ignored.
+// json config:
+// 	securityKey - hash string
+// 	blockKey - gob encode hash string. it's saved as aes crypto.
+// 	securityName - recognized name in encoded cookie string
+// 	cookieName - cookie name
+// 	maxage - cookie max life time.
 func (pder *CookieProvider) SessionInit(maxlifetime int64, config string) error {
 	pder.config = &cookieConfig{}
 	err := json.Unmarshal([]byte(config), pder.config)
@@ -104,6 +121,8 @@ func (pder *CookieProvider) SessionInit(maxlifetime int64, config string) error
 	return nil
 }
 
+// Get SessionStore in cooke.
+// decode cooke string to map and put into SessionStore with sid.
 func (pder *CookieProvider) SessionRead(sid string) (SessionStore, error) {
 	maps, _ := decodeCookie(pder.block,
 		pder.config.SecurityKey,
@@ -116,26 +135,32 @@ func (pder *CookieProvider) SessionRead(sid string) (SessionStore, error) {
 	return rs, nil
 }
 
+// Cookie session is always existed
 func (pder *CookieProvider) SessionExist(sid string) bool {
 	return true
 }
 
+// Implement method, no used.
 func (pder *CookieProvider) SessionRegenerate(oldsid, sid string) (SessionStore, error) {
 	return nil, nil
 }
 
+// Implement method, no used.
 func (pder *CookieProvider) SessionDestroy(sid string) error {
 	return nil
 }
 
+// Implement method, no used.
 func (pder *CookieProvider) SessionGC() {
 	return
 }
 
+// Implement method, return 0.
 func (pder *CookieProvider) SessionAll() int {
 	return 0
 }
 
+// Implement method, no used.
 func (pder *CookieProvider) SessionUpdate(sid string) error {
 	return nil
 }
diff --git a/session/sess_file.go b/session/sess_file.go
index 5d33d0e2..73eec874 100644
--- a/session/sess_file.go
+++ b/session/sess_file.go
@@ -18,6 +18,7 @@ var (
 	gcmaxlifetime int64
 )
 
+// File session store
 type FileSessionStore struct {
 	f      *os.File
 	sid    string
@@ -25,6 +26,7 @@ type FileSessionStore struct {
 	values map[interface{}]interface{}
 }
 
+// Set value to file session
 func (fs *FileSessionStore) Set(key, value interface{}) error {
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
@@ -32,6 +34,7 @@ func (fs *FileSessionStore) Set(key, value interface{}) error {
 	return nil
 }
 
+// Get value from file session
 func (fs *FileSessionStore) Get(key interface{}) interface{} {
 	fs.lock.RLock()
 	defer fs.lock.RUnlock()
@@ -43,6 +46,7 @@ func (fs *FileSessionStore) Get(key interface{}) interface{} {
 	return nil
 }
 
+// Delete value in file session by given key
 func (fs *FileSessionStore) Delete(key interface{}) error {
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
@@ -50,6 +54,7 @@ func (fs *FileSessionStore) Delete(key interface{}) error {
 	return nil
 }
 
+// Clean all values in file session
 func (fs *FileSessionStore) Flush() error {
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
@@ -57,10 +62,12 @@ func (fs *FileSessionStore) Flush() error {
 	return nil
 }
 
+// Get file session store id
 func (fs *FileSessionStore) SessionID() string {
 	return fs.sid
 }
 
+// Write file session to local file with Gob string
 func (fs *FileSessionStore) SessionRelease(w http.ResponseWriter) {
 	defer fs.f.Close()
 	b, err := encodeGob(fs.values)
@@ -72,17 +79,23 @@ func (fs *FileSessionStore) SessionRelease(w http.ResponseWriter) {
 	fs.f.Write(b)
 }
 
+// File session provider
 type FileProvider struct {
 	maxlifetime int64
 	savePath    string
 }
 
+// Init file session provider.
+// savePath sets the session files path.
 func (fp *FileProvider) SessionInit(maxlifetime int64, savePath string) error {
 	fp.maxlifetime = maxlifetime
 	fp.savePath = savePath
 	return nil
 }
 
+// Read file session by sid.
+// if file is not exist, create it.
+// the file path is generated from sid string.
 func (fp *FileProvider) SessionRead(sid string) (SessionStore, error) {
 	err := os.MkdirAll(path.Join(fp.savePath, string(sid[0]), string(sid[1])), 0777)
 	if err != nil {
@@ -117,6 +130,8 @@ func (fp *FileProvider) SessionRead(sid string) (SessionStore, error) {
 	return ss, nil
 }
 
+// Check file session exist.
+// it checkes the file named from sid exist or not.
 func (fp *FileProvider) SessionExist(sid string) bool {
 	_, err := os.Stat(path.Join(fp.savePath, string(sid[0]), string(sid[1]), sid))
 	if err == nil {
@@ -126,16 +141,20 @@ func (fp *FileProvider) SessionExist(sid string) bool {
 	}
 }
 
+// Remove all files in this save path
 func (fp *FileProvider) SessionDestroy(sid string) error {
 	os.Remove(path.Join(fp.savePath))
 	return nil
 }
 
+// Recycle files in save path
 func (fp *FileProvider) SessionGC() {
 	gcmaxlifetime = fp.maxlifetime
 	filepath.Walk(fp.savePath, gcpath)
 }
 
+// Get active file session number.
+// it walks save path to count files.
 func (fp *FileProvider) SessionAll() int {
 	a := &activeSession{}
 	err := filepath.Walk(fp.savePath, func(path string, f os.FileInfo, err error) error {
@@ -148,6 +167,8 @@ func (fp *FileProvider) SessionAll() int {
 	return a.total
 }
 
+// Generate new sid for file session.
+// it delete old file and create new file named from new sid.
 func (fp *FileProvider) SessionRegenerate(oldsid, sid string) (SessionStore, error) {
 	err := os.MkdirAll(path.Join(fp.savePath, string(oldsid[0]), string(oldsid[1])), 0777)
 	if err != nil {
@@ -197,6 +218,7 @@ func (fp *FileProvider) SessionRegenerate(oldsid, sid string) (SessionStore, err
 	return ss, nil
 }
 
+// remove file in save path if expired
 func gcpath(path string, info os.FileInfo, err error) error {
 	if err != nil {
 		return err
diff --git a/session/session.go b/session/session.go
index f41ba85b..d1a44538 100644
--- a/session/session.go
+++ b/session/session.go
@@ -14,6 +14,7 @@ import (
 	"time"
 )
 
+// SessionStore contains all data for one session process with specific id.
 type SessionStore interface {
 	Set(key, value interface{}) error     //set session value
 	Get(key interface{}) interface{}      //get session value
@@ -23,6 +24,8 @@ type SessionStore interface {
 	Flush() error                         //delete all data
 }
 
+// Provider contains global session methods and saved SessionStores.
+// it can operate a SessionStore by its id.
 type Provider interface {
 	SessionInit(gclifetime int64, config string) error
 	SessionRead(sid string) (SessionStore, error)
@@ -61,16 +64,24 @@ type managerConfig struct {
 	ProviderConfig    string `json:"providerConfig"`
 }
 
+// Manager contains Provider and its configuration.
 type Manager struct {
 	provider Provider
 	config   *managerConfig
 }
 
-//options
-//1. is https  default false
-//2. hashfunc  default sha1
-//3. hashkey default beegosessionkey
-//4. maxage default is none
+// Create new Manager with provider name and json config string.
+// provider name:
+// 1. cookie
+// 2. file
+// 3. memory
+// 4. redis
+// 5. mysql
+// json config:
+// 1. is https  default false
+// 2. hashfunc  default sha1
+// 3. hashkey default beegosessionkey
+// 4. maxage default is none
 func NewManager(provideName, config string) (*Manager, error) {
 	provider, ok := provides[provideName]
 	if !ok {
@@ -102,7 +113,8 @@ func NewManager(provideName, config string) (*Manager, error) {
 	}, nil
 }
 
-//get Session
+// Start session. generate or read the session id from http request.
+// if session id exists, return SessionStore with this id.
 func (manager *Manager) SessionStart(w http.ResponseWriter, r *http.Request) (session SessionStore) {
 	cookie, err := r.Cookie(manager.config.CookieName)
 	if err != nil || cookie.Value == "" {
@@ -144,7 +156,7 @@ func (manager *Manager) SessionStart(w http.ResponseWriter, r *http.Request) (se
 	return
 }
 
-//Destroy sessionid
+// Destroy session by its id in http request cookie.
 func (manager *Manager) SessionDestroy(w http.ResponseWriter, r *http.Request) {
 	cookie, err := r.Cookie(manager.config.CookieName)
 	if err != nil || cookie.Value == "" {
@@ -161,16 +173,20 @@ func (manager *Manager) SessionDestroy(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// Get SessionStore by its id.
 func (manager *Manager) GetProvider(sid string) (sessions SessionStore, err error) {
 	sessions, err = manager.provider.SessionRead(sid)
 	return
 }
 
+// Start session gc process.
+// it can do gc in times after gc lifetime.
 func (manager *Manager) GC() {
 	manager.provider.SessionGC()
 	time.AfterFunc(time.Duration(manager.config.Gclifetime)*time.Second, func() { manager.GC() })
 }
 
+// Regenerate a session id for this SessionStore who's id is saving in http request.
 func (manager *Manager) SessionRegenerateId(w http.ResponseWriter, r *http.Request) (session SessionStore) {
 	sid := manager.sessionId(r)
 	cookie, err := r.Cookie(manager.config.CookieName)
@@ -198,20 +214,23 @@ func (manager *Manager) SessionRegenerateId(w http.ResponseWriter, r *http.Reque
 	return
 }
 
+// Get all active sessions count number.
 func (manager *Manager) GetActiveSession() int {
 	return manager.provider.SessionAll()
 }
 
+// Set hash function for generating session id.
 func (manager *Manager) SetHashFunc(hasfunc, hashkey string) {
 	manager.config.SessionIDHashFunc = hasfunc
 	manager.config.SessionIDHashKey = hashkey
 }
 
+// Set cookie with https.
 func (manager *Manager) SetSecure(secure bool) {
 	manager.config.Secure = secure
 }
 
-//remote_addr cruunixnano randdata
+// generate session id with rand string, unix nano time, remote addr by hash function.
 func (manager *Manager) sessionId(r *http.Request) (sid string) {
 	bs := make([]byte, 24)
 	if _, err := io.ReadFull(rand.Reader, bs); err != nil {