Abstract: Main characteristics of insulated gate bipolar transistor （IGBT） and the anti-paralleled diode during switching transient are concluded,and the corresponded switching model is deduced based on which,the loss analysis model is proposed. The influence of conduction current on switching transients has been taken into consideration in the proposed switching model and the waveforms of voltage and current during switching transients of any given switching period can be represented,which lay a foundation for loss analysis of power converters. The novel switching model is suitable not only for the DC/DC converter,but also for AC/DC and DC/AC converters,in which the conduction current vary between the adjacent switching period. Simulink/Stateflow is used to simulate the switching process and analyse the losses. The proposed switching model and loss analysis model have been validated by the simulation and experimental results.