Abstract: With the development of smart grid, a large number of distributed generations are connected to distribution network, which cause great changes in the power supply situation of distribution network, so the fault self-healing strategy is becoming more and more important. Based on the randomness characteristics of the load power, and wind and photovoltaic power generation, the optimal island partitioning model is built. In addition, the calculation method of reliability index on each load bus in distribution network is proposed, and the Monte Carlo method is used to solve the reliability index of distribution network. In the end, through analyzing the IEEE-RBTS BUS 6 system, the validity of the application of optimal island partitioning method to distribution network with DGs and its impact on reliability evaluation of distribution network are studied. In this paper, from the aspect of the power supply reliability, the island partitioning of distribution network with DGs is evaluated quantitatively, which provides certain theoretical basis for evaluating the power supply reliability of distribution network with DG and determining relative fault self-healing strategy.