The concept of “energy internet” combining distributed renewable energy and internet technology provides a feasible path for solving the fossil energy crisis. The energy internet will break the barriers between different energy systems such as electricity, gas and heat, realize the comprehensive utilization of multiple energy sources, and support the wide-scale access of large-scale renewable energy, open and interconnect multi-energy networks, and become a new energy supply network coupling a multi-energy flow system. This paper first summarizes the multi-energy coupling characteristics of the energy internet based on existing research. Then a construction method for a multi-energy flow coupling model is introduced. In line with the structure of the energy network and the form of energy use, the multi-energy flow interaction mechanism of energy internet is analyzed. On this basis, the optimization model of the energy internet, the multi-time scale dynamic optimization method of multi-energy, and the multi-source complementary dynamic optimization method based on spatial scale are analyzed. This will provide a theoretical basis for energy internet construction. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 25190412-1-10).