Bench test studies on effects of the negative pressure factors of seedmetering device including rotation speed of air blower,rotation speed of planting plate and planting rows on pneumatic system of pneumatic rice direct seedling planter were conducted.The results showed that negative pressure of seed-metering device increased with the increase of rotation speed of air blower and decreased with the growing number of seedmetering devices.Rotation speed of planting plate had no significant influence on negative pressure of seed-metering device.The stability of metering quantity of the seedmetering device in pneumatic system needs to be improved.The characteristics model of air blower and seedmetering device are established.The determination coefficients were more than 0.92.The relative errors of both model validation were within -15.92%12.12% and -2.70%5.40%,respectively.It will provide a reference for structural improvement and practical production of pneumatic system in pneumatic direct rice seedling planter.