//把页面从 WordPress 搜索结果中排除
add_filter('pre_get_posts','search_filter');
function search_filter($query) {
	if ($query->is_search) {
		$query->set('post_type', 'post');
	}
	return $query;
}

via:http://fairyfish.net/m/exclude-pages-from-wordpress-search-results/