Abstract: The DJI MG1-P electric four-rotor plant protection unmanned aerial vehicle was used for spraying in the mid-growth-cotton. And the effects of spray parameters and adjuvant type on the deposition and distribution of pesticide mist droplets on cotton plant leaves were discussed. 22% flonicamidonitrile SC and three kinds of spray adjuvants (Beidatong, ND-800, G-2801) were used as test agents, which were sprayed under different spray parameters and different aerial spray adjuvants. As a tracer of pesticide deposition, allura red was employed to detect the distribution of droplet deposition using water sensitive paper and filter paper. The absorbance value of the filter paper elution solution was measured by a spectrophotometer. The absorbance value of the filter paper elution solution is measured by a spectrophotometer in order to calculate the amount of drug solution deposited per unit area, and the droplet density was analyzed by DepositScan software. The test results showed that the flight speed of unmanned aerial vehicle had the greatest influence on the droplet deposition distribution, and the flight height had no significant effect on the experiments using the middle of cotton growth. The adjuvant had a significant effect on the spray deposition distribution. After adding the spray adjuvants, the droplet densities on the upper, middle and lower parts of the cotton canopy were all significantly improved. After adding ND-800 adjuvant, the droplet density on the back of the upper, middle and lower leaves of the cotton canopy increased by 688.9%, 590.9% and 327.5%, respectively. However, the addition of G-2801 and Bidatong adjuvant had no significant effect on the droplet density on the back of cotton leaves.