Abstract: The term "smart city", a foreign term in origin, has gradually come to denote an important policy concept and become a practical carrier of urban construction in China. The multiple-actor characteristic and structure of smart city discourse in the different stages of smart city construction in China is described in terms of policy discourse, and the evolution of policy discourse of smart city from an overseas concept to a policy concept and then to policy practice is analyzed. It is found that there have been three stages from the introduction of the concept "smart city" to its nationwide spread: the concept introduction stage, at which the local government and relevant enterprises form a policy discourse coalition and the discourse of the necessity/rationality of smart city construction is initially formed; the exploration and practice stage, at which people come up with different imaginations on how to build a smart city and the discourse begins to diverge; and the comprehensive development stage, at which smart city construction becomes a national strategy and the discourse of different people begins to converge. Attempts are made to provide an analytical perspective from micro-discourse interaction to macro-policy formation and investigate the process of smart city policy discourse from a concept to practice, which is helpful for understanding the policy process and characteristics against the background of central-local relationship in China.