Abstract: A new method to imitate a 3-D photorealistic single yarn is presented.Various cross-sections can be designed by quadratic B-spline curve,and with random turbulence,the realistic twist effect for the single yarn is achieved.The B-spline surface is constructed according to the principle that a peak point is corresponding to its next peak and a trough is corresponding to its next trough,which can keep the contour of the yarn almost unchanged.The hairiness can also be inserted by deliberately arranging the control points of the B-spline surface.