In order to further improve the distribution network planning model, the topological diagrams of three connection modes, radial, single-loop and two-supply-one-stand-by are abstracted firstly. A planning model of distribution network suitable for multiple power supplies is put forward. This paper takes the risk of power failure, investment cost and operation cost as the objective functions to determine the normal lines of the distribution network, and determine the contact lines and backup lines of the distribution network by the shortest circuit method according to the connection mode constraint. Connection mode constraints are transformed into connection mode units, and load importance and power shortage ENS are transformed into blackout risk by functional relationship, so as to achieve the goal of synergistic consideration of reliability and economy. Finally, Memetic Ant Colony Algorithm (MACA) is used to optimize the model. The proposed method is applied to a 29 node for planning of distribution network. The calculation results show that the presented method can quickly get distribution network planning scheme and its corresponding economy and reliability indices under different connection mode restraints to provide the reference and basis for planning personnel. This work is supported by National Natural Science Foundation of China (No. 51777078) and Science and Technology Project of China Southern Power Grid Company (No. GDKJXM20172942).