# -*- coding: UTF-8 -*-
import os, sys
city = 'cd'
path = "z:\\down\\test11\\" + city

txtpath = 'filename'

isExists=os.path.exists(path)
if not os.path.exists(path):
    print '目录不存在'
    os.makedirs(path.decode('utf-8'))
    print '文件夹:' + path
    print "当前进程工作目录 : %s" % os.getcwd()
else:
    print '目录已经存在....'
    print '文件夹:' + path
    print "当前进程工作目录 : %s" % os.getcwd()


with open(path + "\\{}.txt".format(txtpath), "a") as f:
    f.write('456')
    f.close()

目录已经存在....
文件夹:z:\down\test11\cd
当前进程工作目录 : C:\Users\Administrator

为filename.txt 写入'456'