Abstract: In order to research the dynamics characteristics of involute spur gears with asymmetric teeth, a dynamic model based on virtual prototyping was proposed by setting up an equivalent kinetic model for torsional vibration of asymmetric gears. With this model, the time and frequency domains of vibration characteristic were analyzed taking account of the influence of time-variant mesh stiffness and mesh damping in the course of meshing. These results were compared with numerical simulation and experimental results. It is shown that this simulation method consists with the numerical simulation and experimental method.