With the increasing demand of DC load, the topology of distribution system needs to be reconstructed in order to improve the reliability of distribution system.Two main ways to construct DC distribution system in the present situation include upgrading AC distribution system and constructing DC distribution system.Aiming at above two main ways, novel method based on reliability equivalent network is proposed.Compared with traditional failture mode effect analysis(FMEA) method, the proposed approach not only greatly reduces the calculation burden, but also ensures the accuracy of reliability evaluation results.The case study is carried out based on IEEE-RBTS test system.The availability of the proposed method is authenticated from the aspects of accuracy and efficiency through three steps, including discomposing DC distribution system, load-point reliability evaluation and distribution system reliability evaluation.The reliability evaluation results based on above two ways show that the construction of DC distribution system has higher reliability performance compared with upgrading AC distribution system.Therefore, facing the rapid growth of DC load, the construction of DC distribution system is recommended to satisfy the DC load demand.