Based on the connotation and construction goal of "electricity as the core" modern energy system, this paper proposes that the modern energy system with "electricity as the core" mainly includes the construction of energy base, the construction of comprehensive energy service system, and the interaction between supply and demand between energy base and smart city. The energy base should be fully coupled with wind, water and heat storage, and give full play to the complementarity of different energy forms in space-time characteristics and energy characteristics. It is suggested that the construction of three typical models should be focused on the integration of wind- photovoltaic - thermal -storage, wind- photovoltaic- hydroelectric- storage and wind- photovoltaic -hydrogen-storage. In order to improve the efficiency of terminal energy consumption, this paper gives three application examples of integrated energy service mode in the industrial field, the construction field and the transportation field.Vigorously promoting the construction of energy base on the supply side, promoting smart energy based on comprehensive energy services on the demand side, and realizing the efficient and high-frequency interaction between supply and demand with the support of industrial Internet technology and the guarantee of business model innovation are the inevitable choices for improving the security and flexibility of power system, ensuring the balance of supply and demand, and building a modern energy system with "electricity as the core" .