记一次python写入txt文件正常，但是写入csv文件中文乱码问题

                    with open(city+'.csv','a+') as csv_file:
                        csv_file.write(line)

encoding='utf-8')                  

'utf-8' 换成 'utf-8-sig'

 with open(city+'.csv','a+',encoding='utf-8-sig') as csv_file:
                        csv_file.write(line)

import csv
import os

root_path =os.path.dirname(os.path.abspath(__file__))+'\山东省'
# print(root_path)
city_list=os.listdir(root_path)
# print(city_list)
for city in city_list:
   # print(city)
   city_path=os.path.join(root_path,city)
   # print(city_path)
   for i in range(32):
       file_path=city_path+r'\{}.txt'.format(str(i))
       if not os.path.exists(file_path):
           continue
       else:
           with open(file_path,'r',encoding='utf-8') as f_txt:
               txt_lines=f_txt.readlines()
               # print(txt_lines)
               for line in txt_lines:
                   with open(city+'.csv','a+',encoding='utf-8-sig') as csv_file:
                       csv_file.write(line)
print('写入完成')