使用pre\\u get\\u posts筛选搜索结果：

function search_filter($query) {
  if ( !is_admin() && $query->is_main_query() ) {
    if ($query->is_search) {
      $query->set(\'post_type\', \'custom_post_type_name\');
      $query->set(\'cat\', intval($_POST[\'cat\']); // assuming you have a select with categories with name "cat" 
    }
  }
}

add_action(\'pre_get_posts\',\'search_filter\');