Danwei system is special in Chinese traditional institutions, there is no similar institution in capitalist market economy society or other socialist redistribution economy society. We may find the particularity in the organizational institution change of state-owned enterprises from danwei system to modern corporate system by the perspective of legitimacy which proposed by new institutionalism. In the interaction of organization and environment, danwei system and modern corporate system are both forced by legitimacy, which is just a transformation. In Chinese traditional context, there are also some cultural factors rooted in institutional environment in the transformation of legitimacy, which is more basal in base of legitimacy.