Abstract: In view of the appearance simulation of the yarn, this paper established the yarn cross-section model to determine the control points of yarn. Non-uniform rational B-spline (NURBS) algorithm to fit the points form the appearance surface of the yarn, by modifying the power factor, anti-insert node, modify the control points of the method to modify the yarn surface. In the modified method of control points has been improved, can also modify the number of control points to modify the shape of the yarn surface. The experimental results show that: use this algorithm for yarn simulation, and ensure the appearance of the yarn surfaces are relatively stable; of these three methods can simulation of yarn appearance, the third method simulation effect best in the improved, achieve the expected purpose.