Plant protection UAVs have developed rapidly as a new type of orchard pesticide application equipment. This study was conducted to explore the influence of plant protection UAVs' operation parameters on the properties of droplet deposition. The DJI T30 plant protection UAV was used to affect the influences of spray volume (60 L/ha and 90 L/ha), spray height (2m and 2.5m), with or without an adjuvant and spray patterns (Regular pattern and Orchard pattern) on characteristics of droplet deposition. The test results showed that the interaction of multiple factors has no significant difference in most droplet deposition on various layers of fruit trees. The deposition characteristics of droplets were improved at a spray height of 2 m and a spray volume of 90 L/ha in the presence of adjuvants. In the orchard spray pattern, the penetration of droplet deposition is improved, but the impact on droplet density and coverage is different. Overall, the orchard spraying pattern can achieve better coverage, while the droplet density is the opposite. The spray performance is closely related to the spray volume, with or without an adjuvant, spray pattern, and spray height. The research results provide a theoretical basis for selecting appropriate operating parameters and spray patterns for plant protection UAVs in apple orchards.