$re = '/(<a[^>]*>[^<]*<img[^>]*>[^<]*<\/a>)\r?\n?/si';
$str = '<a href="/in-bai-viet--Choang-n20120711033726647.chn" target="_blank">In<img src="/Images/printer.png" alt="In bài viết này" />
</a>
<a target="_blank" rel="nofollow" href="http://ttvn.vn/">Thiên Lam - TTVN
</a>
<a href="/tinh-yeu-hon-nhan/20120709102954599/Chay-lang-.chn" title="\'abc\'">
abcd
</a>
<a href="/in-bai-viet--Choang-n20120711033726647.chn" target="_blank">In<img src="/Images/printer.png" alt="In bài viết này" />
</a>
<a target="_blank" rel="nofollow" href="http://ttvn.vn/">Thiên Lam - TTVN
</a>
<a href="/tinh-yeu-hon-nhan/20120709102954599/Chay-lang-.chn" title="\'abc\'">
abcd
</a>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php