Abstract: The low utilization rate of pesticides is one of the important factors that affect the agricultural ecological environment as well as the quality and safety of agricultural products, while optimizing pesticide spraying technology is an effective means to improve the pesticide utilization rate. As one of the most important components in the aerial pesticide application in the field, UAV (unmanned aerial vehicle) spraying has developed rapidly with advantages of strong flexibility, high spraying efficiency and fast operation speed. As a key component of aviation spraying system, nozzle for UAV plant protection is mainly divided into 2 categories, i.e. the hydraulic atomization nozzle and the centrifugal atomization nozzle. The common used hydraulic atomization nozzle mainly contains fan nozzle and cone nozzle, and fan nozzle has various types and has been applied more widely. The centrifugal atomization nozzle has an adjustable droplet size with better anti-blocking performance, but the high price and low droplet penetration have restrained its fast development. Besides, the good performance of nozzle can greatly improve the uniformity of the aerial spraying and reduce droplet drift, enhancing the pesticide utilization efficiency. Thus this paper put forward the nozzle performance evaluation index, which included the nozzle type, spray angle, volume median diameter (VMD), features and applications. Beyond this, the amount of droplet deposition, coverage rate and droplet distribution are important indices to evaluate the spray performance. Therefore, the measuring methods of droplets were summarized from 3 aspects, including droplet collection method, droplet deposition test method and instrument test method. Among them, the droplet collection method included magnesium oxide plate method, silicon oil method and test paper method; the droplet deposition test method included colorant method and fluorescent particle tracing method; the instrument test method included phase Doppler particle analyzer (PDPA), particle/droplet image analyzer (PDIA) and laser diffraction analyzer. The traditional droplet size measurement methods such as magnesium oxide plate method and silicon oil method are gradually replaced by paper card method, which is widely used in the measurement of droplet coverage and distribution. The colorant method and fluorescent particle tracing method are widely used in the measurement of droplet deposition, and the instrument measurement method has the advantages of high precision and large amount of information, which can play a great role in indoor experiment. However, the nozzle selection for UAV plant protection often refers to the ground machinery, which lacks standard and professional guidance. The problems of droplet drift and pesticide loss exist in the application of UAV spray, and the utilization rate of pesticides needs to be improved. On this basis, this paper proposed that the rational spray decision should be based on the comprehensive analysis of target crop, spraying demand and spraying environment condition. The target crops information covers crop growth, leaf surface properties and leaf inclination; the spraying demands mainly refer to the determination of appropriate pesticides, dosage forms and adjuvants according to the control objectives of disease control, pest control or weeding; the influence of environmental factors mainly refers to the evaporation and drift of droplets caused by the changes of temperature, humidity, wind speed and wind direction. As the field environment is an uncontrollable environment, it is necessary to develop a selection scheme for the spraying characteristics of high concentration and low capacity for UAV, aiming at the best deposition effect and least droplet drift. Under the influence of spray equipment, target crops and pesticide application environment, the interaction between those factors determines the selection of optimal nozzle and spraying parameters. In this paper, spray angle, anti-blocking requirement, optimum droplet size, nozzle pressure and flow rate are the crucial points for nozzle selection. Finally, the further research is prospected from 2 aspects: the establishment of the specialized nozzle determination system and the research and development of the specialized nozzle for plant protection of UAV.