As a key component of ITER PF converter module, thyristor conducting large current produces a lot of power loss, therefore it is meaningful to study its heat transfer characteristic for improving the performance of PF converter. This paper presents the thermal analysis of the thyristor. A 3D finite-element model with multi material layers is built and simulated in steady state operation. A special temperature rise test scheme is designed and done to verify the analysis result. The simulation is well in compliance with the test result. The modeling method presented in this paper is proved to be practical in thyristor thermal analysis. The proposed measurement method in temperature rise test is also of valuable reference for thermal testing of power semiconductor devices.