In this research, Discrete Element Method (DEM) or in other words, Molecular Dynamics (MD) is employed for simulation of sorting process of granular materials which is done by means of a linear vibratingscreen device.To model the interaction forces between the particles and walls, short range viscoelastic Hertz potential has been used. Spherical and rectangular shapeswere considered for the particles and the screen mesh aperturesrespectively; and a linear vibration is applied to the mesh surface. During the simulation, differential governing equations of the granules motions are solved numerically to predict their behavior. The required programs were developed to perform the simulations using the open source code, LIGGHTS; and the factors affecting numerical computationswere tuned to obtain suitable values. Numerous simulations were done to study the effects of different parameters includingmeshinclination,vibration frequency,vibration angle and apertures' size onthe sorting performance; and the correlations are reported graphically. The obtained results are verified by comparison with the adequate ones reported in open literature. Although the current research is not limited to a special case, some data related to the characteristics of iron pellet and the screen device in Gol-e-Gohar pellet factory are employed for numerical studies.