例如：

<a style="color:#ccc; font-size=14px;" href="/links.html?l=eThaeHZocGVvazVnWkVZRjNNOHZ0VWl3bFlWdnVYbVpTTENWaFcrNWVaaz0%3D">百度</a>
将字符串中style="color:#ccc; font-size=14px;"替换掉

<?php
$string = '<a style="color:#ccc; font-size=14px;" href="/links.html?l=eThaeHZocGVvazVnWkVZRjNNOHZ0VWl3bFlWdnVYbVpTTENWaFcrNWVaaz0%3D">百度</a>';
$pattern = '/<a(.*?)style=".*?"(.*?)>/';
echo preg_replace($pattern, "<a$1$2>", $string);