http://wordpress.org/extend/plugins/wcm-user-language-switcher
I tried wcm language switcher, it only supports for users, not for guest who are not logged in. anyway thanks to kaiser & brasofilo.
Finally, I got a solution with theme switcher plugin
http://wordpress.org/extend/plugins/theme-switcher
I duplicate my theme and keep one is default, then create next one for new-language.
even it takes more space in hosting, it was definitely what I need.
just add to header.php as the follow codes
<?php wp_theme_switcher(); ?> or <?php wp_theme_switcher('dropdown'); ?>
it allowed for all users,guests and also eveyone can switch without logging in.
theme switcher plugin also provide for sidebar widget with dropdown & lists style.