With the application and development of distributed generation technologies,a large number of distribu-ted generators (DGs) are installed in the form of microgrid.In this paper,first,by taking the wind- storage com-plementary microgrid as an example and by considering the operation mode of the wind- storage complementary mi-crogrid in distribution networks,several reliability indices of load and system are calculated via the Monte Carlosimulation algorithm.Next,after analyzing the characteristics of random power sources,a reliability evaluationmodel of the wind- storage complementary microgrid is established.Then,a site selection of wind- power DGs is ca-rried out according to the simulated reliability results,and an island is planned after determining the energy storagecapacity.Moreover,the possibility of malfunction of microgrids after the island formation, which is due to the ru-nning out of energy storage caused by the time- varying load and the DG output,is discussed.Finally,a reliabilitysimulation is performed with the Monte Carlo method for the power distribution network with the wind- storage com-plementary microgrid.It is found that the reliability greatly improves when a microgrid is connected.