An air suction seed drainer was designed and simulated in order to improve the mechanization level of precision seeders applicable for small size grains such as Chinese cabbage seeds.Firstly,the performance of the seed metering device was acquired through tests using performance test-bench of JPS-12,based on which the optimal parameter combination was obtained.Then,the flow field distribution inside the air suction chamber under different vacuum degrees or rotating speeds was analyzed using computational fluid dynamics (CFD) and FLUENT software,and a seed shape model of Chinese cabbage was established based on discrete element method (DEM).Finally,the seed metering device simulation was carried out by a simplified model and grid meshing.The comparison between bench test and simulation result showed that the air suction seed drainer performed best when the rotating speed of seed metering tray is 20 r/min and the vacuum degree of air suction chamber is 2.2 kPa.