The uncertainty and intermittency of renewable resources, the time-varying power generation and radiation of generator sets, and the energy coupling between generator sets in the process of energy trading all bring severe challenges to the stable operation and optimal dispatch of the power system. To this end, the energy management system in the current multi-microgrid system is analyzed. The topology, time scale and dispatch optimization structure in microgrid are discussed. The results show that the microgrid structure is conducive to the construction of new power system and plays an important role in promoting the transformation and reform of power system in the future.