用substr截取毫秒时间戳的前十位就可以了啊 例如：

date_default_timezone_set('PRC');
$time = 1492396179000;
$time = substr($time,0,10);
$date = date('Y-m-d H:i:s',$time);

echo $date;

date_default_timezone_set('PRC');
$mtimestamp = sprintf("%.3f", microtime(true)); // 带毫秒的时间戳
 
$timestamp = floor($mtimestamp); // 时间戳
$milliseconds = round(($mtimestamp - $timestamp) * 1000); // 毫秒
 
$datetime = date("Y-m-d H:i:s", $timestamp) . '.' . $milliseconds;
echo sprintf("%s -> %s", $mtimestamp, $datetime);