Abstract: The legality of public administration has been a long-term question. Under the orientation of post-modernism, the legality of public administration is no longer the traditional concept of preventing administration from suspiciousness, instead, it is the legality of the role of administration played in the democratic governance. Since this problem has never been solved effectively in the administrative area, the post-modernism public administration advocates to destructing the governance mode and bureaucracy cored by “rational people”. On this basis, it suggests reconstructing the legality of public administration by utilizing pragmatism, public energy, and policy network discourse