Abstract: A new ejection mechanism system was designed to improve the uniformity of seed suspension height in seed plate vibrating for air-suction tray seeder. This new ejection mechanism system consists of four springs, one electromagnet and one seed plate. The seed movement rules were recognized through theoretical analysis and dynamic simulation with respect to seed movement. An advanced seed plate was designed, and the second-generation prototype was completed and tested. The test results indicated the hopping heights of the seeds are uniform, which solved the problem of seed movement and grouping, single seed rate greater than 96%, effectively reduced cavity rate under 2%, and increased adsorption rate above 98%. All performance indices meet the agricultural requirements of precision seeding. This study provides a new idea for the structure design of the vibration system.