Abstract: In order to overcome the disadvantage that it is difficult to obtain the optimal planning scheme of the AC/DC hybrid distribution network planning model based on the heuristic optimization algorithm, and to better balance the economy and reliability of the AC/DC hybrid distribution network in the planning meanwhile, this paper proposes a mixed-integer linear programming（MILP） model for the medium-voltage AC/DC hybrid distribution network accounting for reliability costs based on the improved explicit expression method of distribution network reliability and linear power flow constraints. The proposed model aims at the minimization of cost of investment and construction, cost of operation, and cost of reliability. The node construction types and branches in the distribution network are planned and solved. Then, the obtained AC/DC hybrid planning scheme is compared with the AC planning scheme and the DC planning scheme, respectively. Finally, the influence of the converter failure rate on the planning results of the AC/DC hybrid distribution network is analyzed.