Abstract: Air-blast spraying can resist the natural wind disturbance effectively, reduce droplet drift. In order to research the spraying validity and droplets penetration, thes experiment was carried out via a wide-swath air-blast sprayer as the test platform, while 0.1% Rhodamine B as a tracer. Spraying validity test results showed that it had a better spraying validity in the front surface and intermediate section of the target tree canopy, and there was all droplet deposition in the front surface, intermediate section, back surface of the canopy and the section rearwards 10 cm away from the back of canopy. The spraying validity respectively was 100%, 86.2%, 48.3% and 62.1%. The droplets penetration test results showed that, in the front surface, intermediate section, back surface of the target tree canopy, the droplets deposition respectively was 0.028 mL, 0.007 mL, 0.003 mL. There were droplets deposition obviously on the ground near the target tree and the depositions at the sampling points were 0.044 mL and 0.031 mL. The reason lead to droplet depositions in the section rearwards 10 cm away from the back of canopy was air flow around the target tree canopy. It could reduce the deposition of droplets on the ground to shut off the nozzle located lower of the wide-swath air-blast sprayer outlet.