Abstract: The　analysis　of electron beam with weak pulsation in drifting tube filled with plasma was given in this paper, the beam with strong pulsation under the same condition was also studied accurately.The results show that whether in α　area or in β area both the range and wave length of beam pulsation related to initial condition and plasma parameters although their pulsation properties werw different, there existed a optimum plasma density when the other condition was set.