A path planning method for Unmanned Aerial Vehicles (UAV) was proposed based on the online Support Vector Machine(SVM) to ensure UAVs reach the destination safely with the minimum probability of being found and through the shortest path.Firstlythe mathematic model was established and analyzed for the path planning of UAV considering the various constraints.The initial path was given by using A* algorithm to obtain the sample data for UAV.On the basis of the initial paththe online SVMwhich has the features of online traininghigh precision modelsmall training sample and strong approximation abilitywas employed to optimize the path of UAV.Finallythe path planning based on the online SVM was used to the simulation of path planning for UAV.The simulation results proved the effectiveness of the proposed method.