For the problems of long registration time and low accuracy caused by the difficulty of feature extraction during the registration of aviation blade point cloud, a method of point cloud edge contour extraction based on Alpha Shape algorithm is proposed. Using PCA principal component analysis to transform coordinate system of source point cloud, the Y-Z plane of the transformed coordinate system is used as the projection plane, the surface point cloud is projected into planar point cloud, and its planar boundary is obtained by Alpha-Shape algorithm, Compare the planar boundary coordinates with the original surface point cloud coordinates, and obtain the 3D edge point coordinates ,then obtain the surface edge point cloud. In the coarse registration stage,downsampling the target point cloud, the surface edge point cloud and the target point cloud are characterized by the FPFH algorithm,using the random consistency algorithm (SAC-IA)to register the edge point cloud and the down-sampled target point cloud , and the source point cloud is transformed to the initial position that meets the requirements of the ICP algorithm using the parameter matrix obtained from the coarse registration, Finally, the ICP algorithm based on Levenberg-Marquardt (LM) optimization is used to complete the precise registration. The results show that compared with SAC-IA+ICP algorithm, the accuracy is improved by 54% and the speed is increased by 17%.