Provided is an electric transmission line optimal path generation method based on a GIS. The method comprises the following steps of (1), determining a starting point and a terminal point of an electric transmission line path; (2), extracting an area coverage of the electric transmission line path; (3), processing a GIS map, wherein the GIS map is divided into an obstacle area layer, a geomorphology layer and a road line layer in the same coordinate system; (4), processing an obstacle area and constructing a visual graph according to a minimum area rectangular bounding box method; (5), obtaining an optimal path, wherein firstly feasible obstacle avoidance paths are preferred and obtained, then a cost matrix is constructed, finally an obstacle avoidance path of the shortest path is calculated through a Dijkstra algorithm, and consequently the optimal path of an electric transmission line is obtained; (6), counting the number of corners and crossing and spanning times. The electric transmission line optimal path generation method based on the GIS not only has the functions of avoiding obstacle areas and optimizing the generated path, but also has the functions of counting the length of the path and the number of the corners and the like.