The invention discloses a low-overlapping-rate three-dimensional point cloud registration method, and belongs to the technical field of machine vision. The method aims at solving the problems of highregistration difficulty, low precision and the like of two point clouds with low overlapping rate. The method comprises the following steps: firstly, establishing a multi-scale descriptor by utilizingcurvature characteristics of point cloud to ensure that point cloud data is complete and redundant data is minimum; secondly, performing corresponding relation clustering partitioning by utilizing the angle difference of the multi-scale descriptors to obtain an overlapping region of the source point cloud and the target point cloud; and finally, substituting the point clouds of the overlapping region and the corresponding relationship of the point clouds into a convex optimization problem, removing outliers and optimizing the corresponding relationship, realizing coarse registration, and refining by utilizing an ICP algorithm. According to the invention, the useful search range of point cloud registration can be reduced, the registration calculation amount is reduced, and more advantageous registration precision and time efficiency are provided for point cloud data with a low initial overlapping degree. The method can be widely applied to the fields of three-dimensional model reconstruction, cultural heritage management, robot navigation and positioning and the like.