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In order to investigate the relation between the seeding performance of precision spade punch planter of maize and the vibration caused by the simple harmonic excitation of field roughness, a mathematic vibration model between steady state responses of precision spade punch planter of maize and real seed displacement was established. The mathematic model gave the conclusion that the uniformity of sowing seed of planter was mainly decided by next factors, such as structure properties of planter, work velocity of planter, distance between the seed metering device of planter and the surface of till soil, surface conditions, and the adhere of till soil. The comparasion results between theoretical seed distance and experimental seed distance indicated the distributed trend between both distances above. It was proved that the mathematic model could be used to predict and analyze the uniformity of sowing seed.