Abstract: In order to reveal the inherent mechanism of macromechanical behaviour in silos, the discrete element method was used to study the internal contact forces and flow fields during filling and discharging materials. First, the fundamentals of discrete element method were introduced in this paper. Second, a series of physical experirnents were conducted to test the normal forces acting on silo walls and visualize the whole flow patterns during discharge. Finally, with the particle density and bulk packing density considered, the internal forces and velocity fields of particles in silos were simulated using the discrete element method. It was shown that the wall normal forces as well as the flow patterns simulated with the numerical model are in good agreement with the experimental results. So the discrete element method can be used as an auxiliary tool in the analysis of silo flow and design.