In order to effectively study the discharge performance of pulsed power supply for electromagnetic launch, provide technical support for electromagnetic launch and reduce the cost of research and development, the related modeling and simulation work of electromagnetic launch process needs to be studied. A mathematical model for the actual physical process of the projectile was established, a circuit model of the pulsed power source was set up, and the discharge system of pulsed power supply was studied by using the method of combination of these two models. Furthermore, the simulation model of pulsed power supply discharge system based on the multi physical phenomena in transmit process was proposed. The effectiveness of the proposed method was verified by experiments, which lays a foundation for the discharge research of pulsed power supply.