A new method for simulating the solid conveying process in plasticating machine is proposed in this paper The new simulation method is superior to previous ones by having the ability in modeling the movements, in any direction, of solid pellets of any geometry or whether it is densely or sparsely packed. New normal and tangential contact force models are introduced. With the new method the solid conveying process are simulated more realistically. In the simulation, the effects of velocity of the barrel, the sliding frictions of the pellets against the barrel and the screw walls with respect to the solid conveying speed are studied, which coincide with empirical results.