$re = '/该网站共有\s*<b[^>]*>([^<]*)<\/b>/';
$str = '该网站共有 <b style="color:#333">1,647</b></b>
个网页被百度收录 </span>
<a class="c-gap-left" href="http://www.baidu.com/link?url=VJVYQ4ICi27sRCzv-qcP6aqwAFaTejX2cxgqpybZ5hSywsOxqZlnjP29Y930JNV8EHBPc4O7XPBnOOsZTAJRCK" target="_blank">到站长平台分析收录量>></a>
</p>';
preg_match_all($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