98%。A Matlab program based on the discrete element method was developed to simulate the seeds motion in a 3-D vibrated seeder bed. The mechanical interactions force between seeds and also between seeds and the bed were modeled by linear springs, dash-pots and friction sliders. The cubic expansion coefficient, H, was calculated to describe the discrete distribution level of seeds. The simulation results show that, the seeds are separated effectively while the bed vibrated with high frequency and small amplitude, H increases with the increasing vibration strength, kv, and decreases with the seeds initial thickness, hs. The influences of friction coefficient and recovery coefficient on H were analyzed. The ideal active state was obtained at hs≈3.8 and kv=5.65. The experimental results also show that the seeds pickup ratio is more than 98%.