For the scenarios where distributed power sources such as wind power and photovoltaic are connected, an integrated electricity-gas energy system planning method is proposed to consider the reliability of energy supply.The method is proposed. Secondly, considering the energy shortage cost generated by the flexible load of the system and the reliability of the radial network, an optimal planning model is developed with the investment cost, maintenance cost and reliability cost as the objectives. Finally, the improved 12-node distribution network and 10-node gas distribution network are simulated in two stages.Finally, the feasibility and effectiveness of the proposed method are verified by the two-stage planning simulation of the improved 12-node distribution network and 10-node gas distribution network.