Insulated gate bipolar transistor (IGBT) power module is used for power switching transistor devices in the power supply and motor control circuits in both hybrid electric vehicles and electric vehicles. The target of heat flux of IGBT is continuously increasing due to the demand for power rating improvements and miniaturisation. Without suitable efficient cooling technologies, excessively high temperature and uneven temperature distribution can cause high thermal stress, eventually leading to severe module failures. Therefore, highly efficient cooling solutions are highly required. Vapour chamber with phase change can provide quick heat transfer and low temperature gradient. This study proposes a new IGBT structure integrated with vapour chamber. The tests and simulation results indicate that the thermal and thermo-mechanical performances of IGBT integrated with vapour chamber are better than those of the IGBT with copper baseplate module. The thermal resistance between the junction and heat sink is reduced from 0.25 to 0.14 °C/W, and the temperature uniformity is greatly improved due to the phase change in the vapour chamber. The simulation also investigates the thermal stress distribution, deformation and thermal fatigue lifespan of IGBT power electronics module. A reduction of 21.8% in thermal stress and an increase of 9% in lifespan of Sn–3.5Ag solder are achieved.