The pollination of pear trees in China requires a large amount of labor and low efficiency. Based on the liquid pollination technology, the liquid pollination experiment of multi-rotor UAV was carried out with horizontal scaffoled pear trees as the research object. The effects of liquid spraying amount per unit area, flight height and pollination mode on droplet deposition distribution and pollination effect of multi-rotor UAV were investigated. The experimental results showed that the performance of liquid spray pollination operation of multi-rotor UAV was stable, and the variation coefficient in groups of droplet deposition distribution was less than 20%. Droplet coverage and droplet coverage density were positively correlated with the spraying amount. When the liquid spraying amount was 6mL/m2, the change of flight height had a significant effect on the droplet deposition distribution. When the flight altitude was 4m, the coverage and coverage density of droplets were 7.06% and 84.77 droplets/cm2, respectively. The fruit setting rate of liquid pollinated flowers and inflorescence were 49.70% and 85.83%, respectively, which were 91% and 43% higher than that of natural pollination. When the amount of liquid pollination was 4.5mL/m2 and 6mL/m2, the fruit setting rate of the UAV liquid pollination was significantly different from that of the natural pollination inflorescence. Meawhile, there was no significant difference between the UAV liquid pollination and the backpack sprayer pollination inflorescence fruit setting rate, which could reach more than 80%. The above results showed that the higher the coverage and density of droplets were, the higher the fruit setting rate of flowers and inflorescences was. The optimal combination of UAV liquid pollination parameters was obtained when the UAV flying height was 4m and the pollen liquid spraying amount was 4.5mL/m2. The research result can provide theoretical guidance and data support for the optimization of liquid pollination operation parameters of multi-rotor UAV.