Abstract: With the development of new power system containing large-scale renewable energy, electromagnetic transient simulation becomes an important tool for studying that. Because of the large scale and complexity of the renewable energy stations, it is so complicated and error-prone to modeling the electromagnetic model manually. In view of the characteristics of the topology of renewable energy interconnection, this paper puts forward a method of automatic modeling based on unit structure. Based on this, the automatic modeling methods of renewable energy, such as automatic complementation, automatic decoupling and automatic calibration of power flow, as well as the automatic actual model matching, are proposed. This method is verified by an electromechanical data with multiple topologies of renewable energy interconnection system. It shows that this method has high accuracy and can effectively deal with various topologies. The developed program has been successfully applied to the digital-analog hybrid simulation of 220 kV and above system of a larege grid and the modeled new energy stations are more than 100 units. The technology greatly improves the efficiency of studying new power system, and enables the new generation UHVAC/DC power grid simulation platform (NGSP) to provide powerful technical support for the safety and stability of power system.