With the bright prospects of application of large unmanned aerial vehicles (UAV) in artificial precipitation enhancement operation, an UAV artificial precipitation enhancement experiment was carried out in Qilian Mountains.This paper discusses the UAV operating performance and analyzes the change characteristics of the microphysical parameters during the cloud seeding processes on 27 October 2020. The results show that the UAV has the ability of large-scale artificial precipitation enhancement and detection with more than 5 h endurance and good anti-deicing and crosswind resistance capabilities. After the cloud seeding processes, concentration and diameter of cloud particles get increased in every level, and the concentration of low-level cloud particles is significantly higher than that of high level. The change of cloud microphysical characteristics before and after seeding operation is related to cloud position and time to select. Within 20-30 min after the seeding, the concentration of the number of raindrops at the ground decreased at first and then increased, while the effective diameter of the particles continued to increase. The cloud particle spectrum showed the characteristics of an increase in large cloud particles, and the precipitation particle spectrum was broadened.