$permissions = $facebook->api("/me/permissions");

然后使用if检查您需要哪个权限

EX：

if (array_key_exists('publish_stream',$permissions['data'][0])) {
    postToWall();
} else {
    //Does not have permission
}

如果您使用的是FQL

$perms = $facebook->api(array(
    "method" => "fql.query","query" => "SELECT read_stream,offline_access,publish_stream FROM permissions WHERE uid=me()"
        ));
echo "<ul>";
foreach ($perms[0] as $k => $v) {
    echo "<li>";
    if ($v === "1") {
        echo "<strong>$k</strong> permission is granted.";
    } else {
        echo "<strong>$k</strong> permission is not granted.";
    }
    echo "</li>";
}

http://www.masteringapi.com/tutorials/how-to-check-if-user-has-certian-permission-facebook-api/22/