您可以先从演员帖子类型编辑屏幕中删除类别元框，如下所示

 function remove_custom_taxonomy()
 {
    remove_meta_box( \'categorydiv\', \'custom_post_slug\', \'side\' );
 }

add_action( \'admin_menu\', \'remove_custom_taxonomy\' );

function default_category($post_id){
     // check autosave
    if (defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE) {
        return $post_id;
    }

     // check for post type
    if (\'Actors\' == $_POST[\'post_type\']) {
            $Default_category_id = \'23\';
        wp_set_post_terms( $post_id,$Default_category_id , \'category\', ture );
     }

}