Abstract: This paper puts forward the aerodynamic principle of using nonsymmetrical jet for high filling seed frequency and cleaning the surplus seeds.A new type of air precision seedmetering device with high filling frequency has been designed in accordance with this principle.This paper also points out the characteristics of the nonsymmetrical jet in the APSD(Air Precision Seedmetering Device).The turbulence model invorks K-ε model.The numerical predictions are based SIMPLE method.　Through the comparisons between the predictions and the measurements,the validity of the mathematical model is confirmed.The predictions are made out for a large recirculation zone on the APSD chamber which is available for filling and cleaning seeds.This APSD has been demonstrated to be capable of highly increasing discharge seeds frequency of the seedmetering device.It has already been successfully used in the precision planter.