With the progress of coal to electricity transformation, power supply reliability evaluation of coal to radio area has become an important topic. The power supply reliability evaluation model is established considering that the coal to radio area is connected to the edge power supply during the power shortage period. First of all, the evaluation index model of power supply reliability considering the marginal power supply is established by using the average power supply availability index. Secondly, the evaluation process of power supply reliability in the coal to radio area is constructed, and the probability distribution model of the grid connection time of the marginal power supply is established. Based on the probability evaluation method of the operation state of the coal to radio area based on the Monte Carlo simulation method, the power supply reliability is given Assessment steps. Finally, power supply reliability evaluation is carried out for a coal to electricity distribution station area with edge power supply access. The effectiveness and rationality of this method are verified by two evaluation scenarios for power supply reliability index evaluation and comparison.