In order to solve the UAV path planning problem fast and reliably, a new path planning method based on the known distribution of threats was presented. On Matlab-based software platform, the initial safe path was obtained through Voronoi diagram. Then the Dijkstra algorithm was used to search for the shortest path. The split method proposed was used to reduce the inflection point in the shortest path which was calculated by Dijkstra algorithm. Finally, sperv function in Matlab was used to smooth the path for optimal path, and the feasibility of the algorithm and excellent time performance was verified via a series of simulation.