how to list all subdomain in wordpress multiuser

take a look at this plugin :

Multi-Site Site List Shortcode

or if you prefer a snippet then:

$blog_list = get_blog_list( 0, 'all' );
if (count($blog_list) > 1){
    echo '<ul>';
    foreach ($blog_list AS $blog) {
        echo '<li>Blog '.$blog['blog_id'].': '.$blog['domain'].$blog['path'].'</li>';
    }
    echo '</ul>'
}