3D path planning is always slow and in efficient for there are many constraints to be considered while planning,meanwhile,the path is produced by searching in huge space.It is an efficient scheme to improve path planning speed by combining 2D path planning and height planning.We proposed a fast 3D path planning method by planning 2D path with Fast Marching Method(FMM) and making height planning using Sparse A-Star(SAS) searching method,where the environment and maneuverability constraints are processed by stages,thereby,the planning space is reduced.Experiments showed that the proposed method generates path quickly,and the obtained path follows terrain and avoids obstacle well.