Abstract: To reduce droplets drifting and improve the droplets penetration and utilization, 3MQ-600 type air-assisted boom sprayer with air-deflector was designed. Hydraulic motor, axial fan, diaphragm pump and other components were driven by tractor and hydraulic pumps. The new grid-like deflector was installed in the air duct, and the flow structure inside the duct was optimized. Experimental results showed that, compared with no wind screen spraying, the average number of droplets increased by 29.5% and the coefficient of variation decreased by 78.5% along the boom in the uniformity of spraying volume, and droplets drift decreased by 45%, and droplet deposition in the middle and bottom parts of crops reaches 50.8% in the crop canopy droplet penetrability. The machine has high performance and reduces drift droplet deposition performance, better utilization of pesticides.