好的，我这样解决：

        // Redirect guest users
    function login_redirect() {
        global $pagenow; 
        // If user is not loged in and not in the login page
        if(!is_user_logged_in() && $pagenow != \'wp-login.php\')
              auth_redirect();
    }
    add_action( \'wp\', \'login_redirect\' );