Abstract: When the lifetime model of the IGBT module established under the power cycling test is used to extrapolate the lifetime under the actual operating condition, an important premise is that the failure mode and mechanism must be the same under different conditions. Although the load pulse duration ton has been proven to have an impact on lifetime, the impact on failure mode and mechanism is unknown until now. In this paper, 3300 V/1500 A IGBT modules were tested under the same thermal stress but in different load pulse durations, 1 s and 2 s respectively. Meanwhile, the junction temperature, on-state voltage drop and quasi-thermal resistance in each cycle were monitored in real time during the test. The results show that the load pulse duration has a significant effect on the failure mode of the IGBT module. When ton?1 s, all the modules are bond wire lift-off and chip solder intact, but when ton?2 s, the bond wire and chip solder age at the same time. The comparison of Scanning acoustic microscope（SAM） images before and after the test confirmed the experimental results. Furthermore, an electric-mechanical-thermal multi-physics finite element model of the IGBT module was established, and the influence mechanism of the load pulse duration on the failure mode was revealed. This paper can provide guidance for the lifetime prediction and aging monitoring of the high power IGBT module.