A method for patching up a point cloud comprises obtaining a point cloud and a predetermined interval and a filtering parameter of curvature. Then a void in the point cloud which needs to be patched up is identified. A minimum encasing box is created to enclose the void. Points inside the minimum encasing box and outside the void are selected to create a B-spline curve surface. The B-spline curve surface are interpolated by the predetermined interval to obtain a plurality of discrete points which are used to patch up the void. Messy points in the void according to the predetermined interval and the filtering parameter of curvature are determined and deleted. Positions of the points in the void are adjusted along their normal vector directions to smooth the point cloud.