Abstract: With the rapid development and application of plant protection UAV in China, its high-efficiency and low-volume spraying technology has gradually become a research hotspot. At present, domestic and foreign researches on spray additives for plant protection UAV are mainly based on droplet drift and laboratory tests. Few studies have been conducted on the physical and chemical properties of spray additives and the effects of droplet deposition characteristics. Spray additives can reduce the surface tension of the solution and increase the retention of droplets, which is of great significance for improving the utilization of pesticides. Therefore, this study explored the effects of different spray additives on the surface tension of the solution, the change law of the contact angle of the solution on the maize leaves, and the droplet deposition characteristics. In the experiment, surface tension-meter, contact angle measurement, 723S visible spectrophotometer, and XAG XP2020 plant protection UAV were used to measure the surface tension, contact angle, droplet deposition characteristics, and other parameters of six kinds of aviation spray additives (Ultimate, Starguar4A, Starguar4, Bei Datong, Mai Fei, Atplus Mso-Hs 500). Kromekote cards and Mylar were used to sample the droplet deposition characteristics, and DepositScan software was used to measure the droplet density, coverage, DV0.5 and other parameters on the Kromekote cards. The test results showed that the addition of spray additives could significantly reduce the surface tension of the solution and had a significant difference (P=0.000). The surface tension value of the solution after adding the spray additives was reduced by 56.4%-67.8% compared with the pure water solution. Among them, Starguar4A spray additives had the best effect on reducing the surface tension of the solution, but it was not significant difference effects of Ultimate spray additives. The spray additives had different effects on the contact angle of the solution on the maize leaves. The contact angle of the pure water solution on the maize leaves varies from 111.27° to 108.10°. With the increase of time, the contact angle of the spray additive solution on the maize leaves gradually decreases and Ultimate spray additive had the best effect, and the contact angle decreased to 0°after the droplets fall on the corn leaves for 90 s. Adding spray additives can increase the density and coverage of the droplets in the deposition area and sampling area, among which the effect of Be Datong spray additives was the best, and the density and coverage of droplets and deposition were increased by 35.1%, 93.8% and 31.9% respectively compared with the pure water solution. The deposition of the deposition area after adding spray additives varies from 0.049-0.072 μL/cm2, which is increased compared with the pure water solution. Among them, the deposition of Bei Datong spray additives was up to 0.072 μL/cm2. The distribution of the deposition amount of the droplets with the sampling position basically conforms to the normal distribution. After adding spray additives, the DV0.5 of most of the additive solutions had been reduced and there was a significant difference (P<0.05). Except for the increase of droplet DV0.5 by Bei Datong, other spray additives all reduce droplet DV0.5, generally reducing by about 50 μm. Adding spray additives had no obvious influence on the droplet relative span, and there was no significant difference compared with the pure water solution (P<0.05). When plant protection spraying operations were carried out in the field, it can be preferable to use Bei Datong spray additives. Although the surface tension and contact angle of Bei Datong spray additives are not optimal, it can also meet the needs of field use of UAV. Meanwhile, the test can also provide a data basis for further improving the utilization rate of pesticides.