conformist

conformist
/kənˈfɔ:mɪst; kən`fɔrmɪst/ n
person who conforms to accepted behaviour, the established religion, etc 循规蹈矩的人; 墨守成规的人
    She's too much of a conformist to wear silly clothes. 她很古板, 不穿那些奇装异服.

牛津英汉双解词典