In order to reveal the aging process of power device, this article presents a field-circuit coupling simulation method to analyze the dynamic process of power device in power cycling test. Firstly, the aging mechanism of power device is described. Then finite element model is constructed to analyze the electric-thermal-mechanical coupling dynamic process of power device. Secondly, a power cycling circuit model is constructed based on IGBT behavior model to provide power consumption in the specific working condition. After the conversion to M-function of circuit model and finite element model, Matlab scripts is designed to realize data transfer between the two models and output information of thermal resistance, maximum junction temperature and maximum von mises stress as evaluation precursor for aging state of power device. Finally on the established simulation platform, simulation experiment were conducted on the influence of circuit parameters and aging parameters of power devices, demonstrating that this method can achieve aging state analysis of power device, considering the fluctuation of circuit parameter during power cycling test. The co-simulation platform is reasonably designed, ensuring accuracy while effectively reducing the time cost. Working as a digital twin of actual module, the platform can help to provide more aging characteristics with few sensors.