您可能没有正确访问它.您可以直接输出它或将其转换为字符串.(在本例中，强制转换是多余的，因为 echo 无论如何都会自动执行)

You're probably not accessing it correctly. You can output it directly or cast it as a string. (in this example, the casting is superfluous, as echo automatically does it anyway)

$content = simplexml_load_string(
    '<content><![CDATA[Hello, world!]]></content>'
);
echo (string) $content;

// or with parent element:

$foo = simplexml_load_string(
    '<foo><content><![CDATA[Hello, world!]]></content></foo>'
);
echo (string) $foo->content;

LIBXML_NOCDATA 可能会让你的运气更好:

You might have better luck with LIBXML_NOCDATA:

$content = simplexml_load_string(
    '<content><![CDATA[Hello, world!]]></content>'
    , null
    , LIBXML_NOCDATA
);