Abstract: Abstract: Compare with uniaxial single-rotor electric unmanned helicopter (USREUH), the structure of round multi-axis multi-rotor electric unmanned helicopter (RMMEUH) is very different to USREUH, and thus its wind field parameters on rice canopy which formed by rotor airflow are also different. To explore the optimization parameters when the RMMEUH conducted supplementary pollination, in this study orthogonal tests of three factors (including flight operating load, altitude and speed) and three levels were carried out to measure the wind field. The tested RMMEUHs include two 8-rotors electric unmanned helicopters and an 18-rotors electric unmanned helicopter.The measured wind directions included parallel to the direction of flight heading (X), perpendicular to the direction of flight heading (Y), and the vertical direction (Z). The battery's voltage drop was also measured at each takeoff and landing of RMMEUH to estimate its economy. A wireless wind speed sensor network measurement system (WWSSN) was used to measure the wind field parameters of the RMMEUH. The WWSSN consists of several wireless wind speed sensors (WWSS, numbered 1#-10#), a flight global position system (FGPS), and an intelligent control focus node (ICFN). The WWSS was used to measure the wind field parameters on rice canopy. FGPS was used to measure the pose information of the RMMEUHs when they fly over the rice canopy. ICFN was used to control and record the wind field parameters. 1#-9# WWSSs were used to measure the wind field parameters which mixed with natural wind and RMMEUH produced wind. And another one, 10#, was set up far from 9#, was mainly used to measure the natural wind speed. In order to reduce the effect from natural wind speed, treatment rules about natural wind speed were adopted before wind field data analysis. The test results showed that: the width of the wind field at X direction was significantly wider than Y direction; Unlike USREUH, there were only one peak wind speed center at X direction of RMMEUH, while two at Y direction, this phenomena might be caused by the superimposition of multiple rotors of RMMEUH, and the lateral flow of the aircraft was also one of the interferences, as a result, narrowed the width of the wind field at Y direction. Comprehensively considered about the width of wind field and battery electricity consumption, the order of the three influence factors was flight speed, takeoff weight, and flight height. Flight speed of 1.30m/s, takeoff weight of 18.85 kg, and flight height of 2.40 m were suggested as the optimization of the operation parameters for supplementary pollination in hybrid rice breeding using RMMEUH. The results provide references to develop a series of specifications of supplementary pollination in hybrid rice breeding using unmanned helicopter.