Abstract: Because of the influence of power flow, microgrid protective devices action probability is uncertain. Aiming at this characteristic, the paper analyzed the affect of different connection mode probability on the uncertainty of protective devices action probability, and made the influence degree of the connective mode for reliability clear. The model of protective devices action probability was established, the failure rate function of distributed power, energy storage, lines was also built on the basis of that model. Meanwhile, the different wiring microgrid reliability considering the influence of wiring on protective devices was analyzed. Further, a scene change microgrid reliability assessment method was proposed based on enumeration method and the shortest method. Finally, the simulation put a low voltage microgrid in Guangxi as a practical example, using the component failure rate model proposed in this paper, evaluating the reliability of microgrid whether to consider the uncertainty of protective devices action probability, the difference of scenes, connective mode, and analyzes the results.