The path fairing technology will ensure a flyable path for UAVs. Firstly, planning space was given by using Voronoi graph and the dynamic programming search algorithm was used to get an initial path: Secondly, the properties of CS curve were studied, based on which, a path fairing method was put forward; Thirdly, through combining the flying constraints into CS curve, the optimal path faring model was built based on CS curve; Lastly, the simulation was presented and the results show that the path faring algorithm can not only ensure the path is flyable, but also ensure UAVs' safety.