For a screening process, the collision and penetration phenomena between particles and screen plate is standard behavior and with collision the mechanical energy of the vibrating screen can be transmitted to the feed. In order to recognize further the collision process and the law of penetrating motion, with the spring-dashpot-slider contact model of the distinct element method (DEM), a mathematical model which can describe the collision process has been established and a program for simulating the motion of a single particle on the screen plate developed by VC++. NET. To evaluate the handling capacity of the screen that deals with difficult screening material, an instantaneous penetrating coefficient is defined. The moving period of the screen plate is divided into four stages. By analyzing the state of contact collision at each stage, it is pointed out that the collision ranging from 3π/2 to 2π period is the most favorable aperture for penetration of particles, while the collision ranging from π/2 to π period is the most unfavorable. The numerical simulation result further indicates that increasing the amplitude of the screen plate has a much greater effect on the augmentation of instantaneous penetration coefficient than increasing the vibration frequency.