Abstract: To study the effectiveness of the plant protection drones in a happy chestnut garden under different flight parameters, using DJI T16, T20, T30 plant protection drones spraying test of chestnut tree, based on different models, height, speed combination of DV1, VMD, NMD, fog spectrum width, droplet density, coverage, pesticide deposition data, reveal the UAV fog particle size distribution rules, and choose the best flight combination. In the case of the same cultivation mode, Chinese chestnut “Funing 15” as the test material, first on the chestnut garden trees research selected, after the spray experiment, and then through the droplet test software for data, using DPS processing system and SPSS software to analyze the data, the plant protection drones under different flight parameters, and finally choose the best flight combination according to the evaluation system. The analysis results show that the performance of the T30 plant protection UAV was better than T16 and T20 under different flight parameters. When the flight altitude of the UAV was fixed, the DV1 value and the droplet spectrum width showed a positive correlation with the flight speed, while the VMD value and the NMD value showed different trends depending on the drone model. For the T16 UAV, with fixed altitude parameters, the droplet density decreased the increasing flight speed. For the T20 UAV, with fixed speed parameters, the droplet density increased with increasing flight altitude. The T16 drone showed a negative correlation between flight speed and pesticide deposition, while the T20 drone showed a negative correlation between flight altitude and pesticide deposition. The DJI T30 plant protection UAV, with a flight altitude of 2 m, a flight speed of 1 m/s, and a spray range of 7 m, showed the best effectiveness in flight prevention on Chinese chestnut.