Constructing a multi-energy supplement system that combines heat, gas and other forms of energy, with electric power as its main energy, and has complementary advantages in multiple parts of production and consumption, is the key for improving energy efficiency, promoting clean energy development, and building energy Internet. Firstly, according to the distributed energy (such as wind, light, etc.) stability model, the smart city multi-energy supplement system architecture is constructed. Secondly, by comprehensively taking the investors, power companies, electricity customers and other energy interest bodies into consideration, the smart city multi-energy supplement system planning model on the conditions of power flow, node voltage with complementary energy, and installed capacity, is built. Thirdly, the improved genetic algorithm is introduced to determine the optimization flow of the model, and the node location and capacity of the energy network of multi-energy supplement system are optimized. The results show that the proper planning of multi-energy supplement system is helpful to the development of energy supply in smart city to be cleaner and more sustainable.