Due to the long seed protection board structure,there are some machine empty travels in the early stage of seeding when 2BZXJ metering device series insert seed in the process of soybean plot breeding. In addition,the direction of seed discharge is the same as the advance direction of the seeder,the drop point displacement of seeds on the ground is large,and the qualified rate of plant spacing is low. Regarding the problems above,a special seed metering device for improved breeding is designed,which removes the seed protection plate,adds seed cleaning knife and seed metering groove to solve the problems of seed storage,seed mixing and empty travel of machine and tools. The ideal mathematical model of seed placement is established. The optimal location of seed placement is determined by combining with the actual structure of seed plate to solve the problems of large rolling spring displacement and low qualified rate of plant spacing. The discrete element simulation software EDEM was used to simulate and compare the draw motion at different stages of the seed metering process. The results showed that the improved breeder seeder planted earlier. The average displacement of the seeds dropped to 46% of the original average displacement,with the mean square error of displacement reduced to 1.95 mm. The average displacement fluctuation was smaller,with more stable plant spacing. Results of field comparison test showed that there are no residual seeds in the improved seeding tray,and the seeding belt was advanced. When the operating speed of the seeding machine is 0.7 m/s,the speed of the seeding device is 24 r/min,and the seed distance is 7 cm. The overall increase of the grain distance qualified index was 6.8 percentage point.The replay index and the missed broadcast index decreased by 3.4 percentage point and 3.41 percentage point. The test results verify the correctness of the simulation results. It will provide a reference for designing and studying the improved seed metering device.