The efficiency of sizing, the energy consumption, noise and vibrational pollution is highly affected by the vibrational parameters of screens. To allow the smooth and energy efficient functioning of the screen, frequency optimization is inevitable. In this paper, the optimal vibrational parameters were determined partly by using analytical methods. The analytical model deals only with the movement of one spherical grain in a non-inertial reference frame. By using the analytical model, an optimal frequency range for screening was determined, but with this method it is still not possible to take into account the interaction between the particles. In order to deal with this problem, discrete element method was used to model the vibrational screen, and to take into account the collision between particles. By using the discrete element model, the domain of optimal vibrational parameters for efficient screening procedure were more precisely determined.