好吧，我是这样做的：

add_filter(\'nav_menu_css_class\' , \'special_nav_class\' , 10 , 2);
function special_nav_class($classes, $item){
     if(is_category() && $item->title == "Blog"){ //Notice you can change the conditional from is_single() and $item->title
             $classes[] = "special-class";
     }
     return $classes;
}