Abstract: The flight parameters of plant protection UAVs have an important influence on the fog droplet distribution and crop protection effect. Orthogonal tests were conducted by selecting the parameters of UAV spraying height, flight speed and sprayer angle to explore the effects of the three flight parameters on droplet coverage uniformity and crop surface coverage. The response surface results showed that the sprayer angle and flight speed had a significant effect on droplet coverage uniformity（p＜0.05）, and appropriate adjustment of spraying height and flight speed could improve droplet coverage uniformity and crop surface coverage. The optimal plant protection UAV flight parameters are spray height 30 m, flight speed 10 m/s, and sprayer angle 45°, which can significantly improve the droplet coverage uniformity and crop surface coverage, and thus improve the crop protection and management effects, and the results of the study can provide guidance for the actual operation of plant protection UAVs.