Abstract: Distribution network of power system reliability is an integral part of the reliability of the three power system reliability, as opposed to the study of power generation and transmission system reliability, it has always been weak, especially the complex distribution network reliability. The paper started with the analysis of the mechanism of distribution network reliability by choosing proper index, introduced entropy weight of the TOPSIS method to the reliability assessment, established the application model on a distribution network. The results obtained can help for decision-making of the distribution network reliability of power system.