Segmentation of 3D object from complex point cloud is usually performed in 2D space by using 2D algorithms. This paper presents a novel 3D algorithm for segmentation of complex point cloud. A closed B-spline surface is selected as 3D elastic model. After initialization, control points of B-spline surface are attracted by a 3D force field and move to the surfaces of target object. 3D GVF derived from the complex point cloud acts as the force field. Finally, the deformable B-spline surface can enclose the target surfaces. Points belonging to target object are segmented and mini-defects are repaired. Experimental results show the efficiency of the proposed 3D algorithm.