Abstract: Air-blowing vertical-rotor type precision seed-metering device can be used at the atmosphere air pressure and at air-blowing pressure of 8-35 kPa for seeding corn and soybean. In order to study the influence of design parameters on seeding performances, uniform design was used to implement the seeding performance test of an air-blowing vertical-rotor type precision soybean seed-metering device at the atmospheric air pressure in a laboratory. The regression models of seeding performance test were processed into figures with Matlab 6.1 software. The effects of the device structure parameters on the performance were investigated. The seed-filling angle, the seed-cleaning angle and the operating speed, were sensitive in the experiment, and 6 levels for each factor were selected. The qualified rate of seed spacing and seed filling rate have similar varying trend, and both optimized value thresholds are the same. The optimized results show that seed-filling angle is 46o, and the seed-cleaning angle is 55o.