Abstract: The purpose of this paper was to improve the planning level of medium voltage distribution network. On the basis of the shortest path and minimum load moment algorithm, and under constraint conditions such as physical conditions, branch current, node voltage conditions, and so on. The method was proposed, which could be used to determine the main line, to connect load node, to automatically search the cross point (intermediate nodes), and to select section of the lines. The ordering technology of nodes and branches were presented before and after the lines connected, and the adjacent join points between two lines could be automatically searched for connecting adjacent lines hand in hand. Finally the function of automatic routing was achieved between adjacent lines. By calculation, analysis and comparison of the actual data from rural power network, the real example planning results showed that the proposed approach could automatically form network, choose the type of each branch of the network, ensure the branch current, active power loss rate and node voltage of the two lines in the area of constraints before and after the lines were connected, and indicated that it was an effective optimal planning method of distribution network. The method could provide the necessary support of data and technology to optimal planning distribution network.