import random
Maclist = []
for i in range(1,7):
    RANDSTR = "".join(random.sample("0123456789abcdef",2))
    Maclist.append(RANDSTR)

RANDMAC = ":".join(Maclist)
print RANDMAC

--------------------------------运行结果-----------------------------------
e4:13:0e:1a:73:f5