>>> from urllib import parse
>>> url = 'http://www.baidu.com/s?wd=codeif.com&spt=1'
>>> bits = list(parse.urlparse(url))
>>> bits
['http', 'www.baidu.com', '/s', '', 'wd=codeif.com&spt=1', '']
>>> qs = parse.parse_qs(bits[4])
>>> qs
{'wd': ['codeif.com'], 'spt': ['1']}
>>> qs['wd'] = ['sina','@www']
>>> qs['pg'] = [8]
>>> del qs['spt']
>>> qs
{'pg': [8], 'wd': ['sina', '@www']}
>>> bits[4] = parse.urlencode(qs, True)
>>> bits
['http', 'www.baidu.com', '/s', '', 'pg=8&wd=minicn&wd=%40www', '']
>>> url = parse.urlunparse(bits)
>>> url
'http://www.baidu.com/s?pg=8&wd=minicn&wd=%40www'
>>>