举例说明：

l = [{'a': 123, 'b': 1234},
        {'a': 3222, 'b': 1234},
        {'a': 123, 'b': 1234}]

seen = set()
new_l = []
for d in l:
    t = tuple(d.items())
    if t not in seen:
        seen.add(t)
        new_l.append(d)

print new_l

输出为： 

[{'a': 123, 'b': 1234}, {'a': 3222, 'b': 1234}]

参考为https://stackoverflow.com/questions/9427163/remove-duplicate-dict-in-list-in-python