Abstract: The high power press-pack IGBTs (Insulated Gate Bipolar Transistor) devices are more suitable for flexible HVDC high power system. It is inevitable to meet the requirements for reliability evaluation of press-pack IGBTs. In this paper, a reliability modeling of press-pack IGBTs considering material fatigue is proposed. Firstly, the electro-thermal-mechanical multi-physics simulation model of single-chip press-pack IGBT device is established and the effectiveness of the IGBT simulation model is verified by experiments. Secondly, the reliability model of single-chip press-pack IGBT device is established considering the fatigue life of materials and the weak points of each layer of single-chip device are analyzed. Finally, the multi-physics simulation model of multi-chip press-pack IGBTs is established based on the actual structure. The stress distribution of the devices is analyzed, and the failure rates of each chip and multi-chip devices are calculated. The results show that the temperature and von Mises stress distribution inside the press-pack IGBTs are uneven. The maximum values are located at the edge of the contour of the contact between the IGBT chip and the emitter molybdenum layer. The chip current, temperature and thermal-mechanical stress distribution are uneven in the multi-chip device. The reliability level of the internal chip is obviously different because of uneven stress distribution in multi-chip devices. The chip at the corner of the device bears the maximum stress and the reliability is the lowest.