Abstract: The calculation method of material energy dissipation coefficients was introduced to solve the problem of snakelike deviation in the burden distribution of a parallel-hopper bell-less top,which leads to an asymmetrical burden surface and the out-of-control of adjusting gas permeability in the burden layer.The effects of particle velocity direction on the effective length of falling movement in the chute and the particle velocity at the chute outlet were analyzed.Some reasons for snakelike deviation and the drop-point differences of charging trajectories were also discussed.It is concluded that the particle collide trajectory in the chute is not an ellipse shape but two semi-ellipses,and the long axis of the smaller semiellipse equals the short axis of the larger semiellipse.