The invention discloses a path planning method of a mobile robot. The method comprises the following steps: acquiring environment information to generate an occupancy grid map; calculating and generating a voronoi diagram; smoothing the voronoi diagram; generating a final planning path based on the smoothed voronoi diagram. The invention adopts the voronoi diagram to ensure that the path planningis always in the middle of the obstacles on two sides, and normally walks under the premise of ensuring that the obstacles will not be touched. According to the path planning method of the mobile robot, in the process of generating the voronoi diagram, the voronoi diagram is generated based on Delaunay triangulation, and the b* pathfinding algorithm is used for fast path planning based on the voronoi diagram, thereby solving the problem of global path planning in real environment; and moreover, the method is simple, scientific and reliable.