With the advancement of Unmanned Aerial Vehicles (UAV) technology, aerial spraying has been rapidly increasing in the agricultural field. Dronesoffer many advantages compared to traditional applicators, but they pose challenges such as spray drift risk and spray uniformity. To address theseissues, it is essential to understand the characteristics of complex airflow generated by drones and its consequences for the spray performance. Thisstudy aims to identify the air velocity distribution of drone downwash and the resulting spray deposition distribution on the ground, ultimately proposingoptimized spraying widths and criteria. Experiments were conducted using two agricultural drones with different propeller arrangements under variousflight and measurement conditions. The results showed that during hovering, the downward airflow affected the area within a distance of the radiusof the blade (R) from the center of the drone. When the drone was flying, the downward airflow was effective up to a distance of 2R. Dropletdeposition was concentrated at the center of the drone during hovering. However, during flying, the droplet deposition was more evenly distributed upto the distance of R. The drone downwash and droplet deposition were significantly different during flying compared to the ...