腾讯的NTP时间Ip：[http://cgi.im.qq.com/cgi-bin/cgi_svrtime]

NTP时间服务器–百科

using System;
using UnityEngine;
using System.Collections;

public class IntTime : MonoBehaviour
{
    private string timeURL = "http://cgi.im.qq.com/cgi-bin/cgi_svrtime";
    IEnumerator Start()
    {
        WWW www = new WWW(timeURL);
        yield return www;
        DateTime date = Convert.ToDateTime(www.text);
    }
}