To evaluate the effect of power electronic devices failure on microgrid’s operational reliability, a short-time outage model of power electronic devices considering operation condition influence is proposed. Firstly, it is pointed that the failure rates of IGBT and power diode are tightly connected with microgrid’s operation conditions. According to the power dissipation model and thermal model of devices, the short-time outage model is built. Using scene analysis method, a complete set of reliability evaluation method for microgrid operation based on the established model is proposed to evaluate the impacts of devices failure on microgrid operational reliability index. And the proposed evaluation method is used on the improved benchmark test system. The simulation results show that devices’ failure has negative effect on the microgrid reliability, and the new reliability model can provide more accurate and comprehensive information than traditional evaluation methods. This work is supported by National Natural Science Foundation of China (No. 51407128).