import re
pattern = re.compile(
    '\xe4\xba\xa4\xe6\x98\x93\xe9\x87\x91\xe9\xa2\x9d\xef\xbc\x9a(\\d+\\.?\\d+)\xe5\x85\x83'
    , flags=re.LOCALE)
for line in open('xx.txt'):
    match = pattern.match(line)
python regular expression with utf8 issue