Objective In order to explore the effect of reduced pesticide application on the control effect of rice planthopper by multi-rotor plant protection UAV and promote the development of reduced pesticide application technique for rice.Method Field experiment was carried out using an M45 multi-rotor plant protection UAV for rice pesticides application. We used two spray volumes of 15.0 and 22.5 L/hm², and three pesticide dosages of 100%, 90%, and 80% of the conventional artificial control dosage. The effect of different spray volume and reduced dosage on the droplet deposition and the control of rice planthopper were analyzed.Result The droplet deposition in the upper part of the rice canopy was significantly higher than that in the lower part of the canopy. The differences of two spray volumes and three dosages on the droplet deposition were not significant. At the same time, the number of rice planthopper decreased significantly after one week of treatment. Under the condition of the same spray volume, the effect of reduced dosage on the control effect of rice planthopper was not significant. Rice spray dosage of 80% of manual application met the requirement of rice planthopper control.Conclusion The spray dosage of 80% can be considered as feasible dosage in the UAV application for rice. The results provide useful reference for promoting the reductions of pesticide application for rice and the operating cost of rice plant protection.