首先用命令pip install itchat安装itchat，然后进到你要获取的群里去选择“保存到通讯录”那里将选项滑到右边选上，没有保存到通讯录的群是取不到信息的。
以下代码在Win7和Python3.7里调试通过。
__author__ = 'Yue Qingxuan'
# -*- coding: utf-8 -*-
import itchat
import time
import datetime
from itchat.content import TEXT
roomslist = []
itchat.auto_login(hotReload=True)
def getroom_message(n):
#获取群的username，对群成员进行分析需要用到
itchat.dump_login_status() # 显示所有的群聊信息，默认是返回保存到通讯录中的群聊
RoomList = itchat.search_chatrooms(name=n)
if RoomList is None:
pass
#print("{0} group is not found!".format(name))
else:
# print('取得：',RoomList[0]['UserName'])
return RoomList[0]['UserName']
def getchatrooms():
#获取群聊列表
roomslist = itchat.get_chatrooms()
#print('列表',roomslist)
return roomslist
print("程序开始：",datetime.datetime.now())
for i in getchatrooms():
roomslist.append(i['NickName'])
with open('群用户名.txt', 'w', encoding='utf-8')as f:
f.write("你一共加入了{0}群".format(str(len(roomslist))))
for n in roomslist:
ChatRoom = itchat.update_chatroom(getroom_message(n), detailedMember=True)
f.write('\n\n------------------------------群名称：'+ChatRoom['NickName']+"该微信群一共有{0}个成员".format(str(len(ChatRoom['MemberList'])))+'----------------------------------\n')
#print("ChatRoom",ChatRoom)
for i in ChatRoom['MemberList']:
f.write('省份：'+i['Province']+" NickName为："+i['NickName']+" RemarkName为："+i['RemarkName']+'\n')
f.close()
print("程序结束：",datetime.datetime.now())
