如果要输出受信任的html，请使用html_entity_decode.

$orig = "I\'ll \\"walk\\" the <b>dog</b> now";

$a = htmlentities($orig);

$b = html_entity_decode($a);

echo $a; // I\'ll &quot;walk&quot; the &lt;b&gt;dog&lt;/b&gt; now

echo $b; // I\'ll "walk" the <b>dog</b> now