The invention discloses a power distribution network medium-voltage line route planning method based on city utility tunnels, and belongs to the technical field of power distribution network planning. The method mainly comprises the following steps: S1, establishing a medium-voltage line power supply planning area; S2, establishing a medium-voltage line route planning model; S3, optimizing a line route based on Dijkstra algorithm; S4, completing line connection on the basis of an increment shortest path method. The route planning is divided into two steps by establishing a medium-voltage line route planning model in power distribution network planning under the construction background of new city district utility tunnels: firstly using a shortest route method to primarily form a power supply network, and realizing optimization for cable route in grid to complete trunk line planning; and then completing line connection based on an increment shortest route method. Compared with a heuristic algorithm, the method has the characteristics of clear concept, high calculation speed and good planning effect. The planned power distribution network medium-voltage line is applicable to the construction condition of city utility tunnels, and is minimum in comprehensive investment cost and shortest in cable route.