Abstract: The basic principle,method and characteristics of the mass-spring model are analyzed.The cloth is digitized as the mass grid with square distribution,the spring connections acting upon mass are replaced by the connections of rigid rod,the external forces acting upon mass are transmitted to the adjacent mass directly through the rigid rod,and the mass-rod model is constructed.According to Newton basic physical law,the mechanical equation of cloth is derived.The 3-D location of the mass is calculated using Verlet integration,the characteristic of rigid-rod restriction comes true using Jacobi relaxation,and cloth 3-D simulation is completed.In the meantime,the collision object is set,the handling of cloth in collision with outside object is accomplished.The adaptability of the model′s multiple constraints is verified.The model is simple and practical,its algorithm is stable and convergent.The excellent real time effect is obtained.