Abstract: The existing power semiconductor device model based on ambipolar diffusion equation (ADE) can only describe the carrier distribution of quasi-neutral region precisely, leading to a limited accuracy when it is applied to modeling of high-voltage power device. In this study, a drift-diffusion model (DDM) based modeling approach with improved accuracy is proposed and applied to the integrated gate commutated thyristor (IGCT) circuit model.By characterizing the IGCT, the analyses reveal that there are the different orders of solving variables, and the characteristic parameters determined by high doping concentrations are the main factors.Moreover, the model stability and execution speed are improved by analytically modeling the highly doped region, by simplifying the boundary conditions of base region calculation, and by using a moving mesh method to solve the DDM equations. Finally, the simulation and experimental results of double-pulse test of IGCT show that, with high simulation speed comparable with ADE-based model, the proposed circuit model is superior to the existing models in its characteristic modeling at turn-off oscillation and punch-through stages.