Abstract: Accurate calculation of transient temperature field for thyristor module is meaningful to improve the reliability of the device application. Therefore, the characteristics of transient thermal analysis and modeling method of the thyristor are discussed, a novel method for calculating efficiency and accuracy is proposed. The highest temperature change curves are obtained according to the fast calculation of transient temperature field for variety complex conditions by developed program. The calculation results show that the grid number of direct reduction can greatly decrease the computing resource and time, the consistency of boundary condition can be guaranteed by the interpolation of convective heat transfer coefficient, and the calculation accuracy and efficiency can be achieved by model order reduction method. The proposed method provides a theoretical basis for the thermal design of thyristor module.