可能是太简单的缘故，在google中查询不到，所以贴一下免得忘记了：
import os
from os.path import join, getsize
def getdirsize(dir):
size = 0L
for root, dirs, files in os.walk(dir):
size += sum([getsize(join(root, name)) for name in files])
return size
if '__name__' == '__main__':
filesize = getdirsize(r'c:\windows')
print 'There are %.3f' % (size/1024/1024), 'Mbytes in c:\\windows'