The invention discloses a three-dimensional point cloud full-automatic registration method. The method includes the following steps that: two groups of point cloud data A and B are inputted, the normal directions and boundaries of the two groups of point cloud data A and B are calculated, and the data are simplified, and boundary points are removed; three-dimensional feature processing is performed on the pre-processed point cloud data A and B, so that corresponding three-dimensional feature descriptors Key A and Key B are obtained; as for each datum in the Key A, a plurality of points which are nearest to each datum in the Key are searched in the Key B, and are adopted as preliminary corresponding points, and corresponding points which do not satisfy a predetermined condition are removed from the preliminary corresponding points, so that a final candidate point set can be obtained; rigid transformation matrixes are calculated for each group of candidate point pair so as to form a candidate matrix set; and confidence factors are calculated for each candidate matrix according to the candidate matrix set, a candidate matrix with a maximum confidence factor is selected as a final rigid transformation matrix, and source point cloud is transformed to a coordinate system of target point cloud through the rigid transformation matrix.