Regarding the vibrating seeds box of magnetic cylinder seeder as the research subject and making simulation and analysis for the motion law of seeds which supplied by seed box base on DEM (Discrete Element Method). Researching the mechanism of the seed supply and analyzing the condition of seed supply by the vibration of seed box, when the frequency change from 10Hz to 50Hz and horizontal and vertical amplitude of the seed box are 0.5mm. The results shows that the vibrating frequency has greater influence on the seed supply; seeds can’t be supplied when the vibrating frequency less than10Hz; seed can be supplied best and seeds thickness nearly the cylinder wall is highest when the vibrating frequency equal to 40Hz.