Abstract: Based on the discrete mathematics and computer technology, a numerical simulation model of a rubbing pair system of cam plat-bottomed follower was presented. By introducing the concepts of position vector and wear step, the continuous wear process was discreted, which made it possible to predict the wear life and reliability of the cam and the dynamic simulation of the movement law of the follower. It was found that the complex wear process could be simulated by the present numerical method, which made it feasible to get rid of disadvantages of the traditional research method only relying on experiments. By establishing a series of discrete quasi static models, the dynamic non-linear wear problem that could not be solved by the classical calculus was resolved. Thus the present numerical method could find good prospects in practical engineering application.