With agricultural aircraft spraying operations flight speed fast, spraying high work efficiency and strong ability to deal with unexpected disasters and overcome the agricultural machinery or artificial cannot enter the homework problems, and its development prospects have been attached great importance in the field of agricultural plant protection.In the field of agricultural engineering, the multi rotor Unmanned Aerial Vehicle (UAV) has the advantage of low cost and easy manipulation, which is suitable for aviation spray flying at low altitude, low speed and low amount.The results of the analysis of a SH-8 UAV Model with eight rotors.Under the condition of laboratory simulation, fan is used to simulate the rotor rotation, to discuss rotor airflow speed in the conditions of different output of spray flow, in order to get pesticide droplets deposition effect space distribution map.In this experiment, we use the fan of two leaves to simulate the odd rotor of multi rotor UAV, make it placed in a suitable shelf for aerial spraying of 1.5 to 2m altitude.Then we can take use of the DC motor and gear pump for the pesticide liquid to reach applied pressure so that we can get different output of spray flow, through the fan nozzle to spray the liquid, with water sensitive paper to collect droplets, showing a droplet horizontal deposition effect map.In the aspect of the software, the Image of droplet horizontal deposition effect map processing software provide us with the analysis of droplet size, coverage rate and deposition uniformity.At the same time, using thermal infrared imager, taking advantage of its'sensitivity of different temperature, droplet deposition process could get the droplet drift deposition maps on the perpendicular direction.In the combination of the water sensitive paper droplet horizontal sedimentary distribution map and the droplet vertical deposition distribution combination chart from thermal infrared imager, we can get the three dimensional droplet deposition maps construction obtained each experiment under the condition of droplet deposition space distribution effect picture.The results show that the existence of rotor rotational flow velocity and different spray volume conditions all can make the 3D droplet deposition effect maps different.The air rotor will bring certain influence on the droplet drift in the process of aerial spray pesticide.When spray flow is larger, droplet drift will be smaller, more serious.However, to some extent, larger spray flow can improve the droplet deposition uniformity.The application of agricultural aviation is effective guarantee for the realization of national ecological security and food security.But there are still insufficient on aerial spraying application basic theory, low altitude spraying settlement rules, aerial electrostatic spraying technology, aviation of variable rate spraying technology and other aspects in our country.The results for the analysis of multi rotor UAV research on droplet deposition effect map made a theoretical foundation of optimal choice of rotor speed for aviation spray, which is a kind of aviation spray key technology.