More and more distributed generations will be embedded into the distribution network. This will impact the operation mode of distribution network, and the reliability evaluation method will change at the same time. This paper presents a reliability index calculation method for distribution network connected with micro-grid. First, assuming the basic unit for power changes is an hour, the paper establishes the sequence model of wind turbine generator, photovoltaic generator, and energy storage device. The energy storage device charge-discharge strategy is also formulated. According to the differences of each unit affected by the fault, the network will be divided into different types of areas, and then the outage time of each load point is determined by the result of area division and load optimization in the island. On this basis, the reliability indices are calculated by Monte Carlo simulation. Taking the improved IEEE RBTS BUS6 network for example, the indices before and after connecting micro-grid are calculated, thus the role that micro-grid can play in the improvement of distribution system reliability is verified.