The spray boom of the existing large boom sprayer mostly adopts traditional truss structure. With the increase of spray boom length, the quality of the whole machine is increased accordingly, which is prone to the problem of car trap. At the same time, The balance control of spray boom is more difficult, which reduces the reliability and convenience of the whole machine. Especially in paddy field spraying operation, the function of large boom sprayer is greatly limited. Aiming at the problems of the spray boom in the traditional truss structure, a kind of rotors hovering spray boom was proposed.The advantages of high endurance of ground machinery, large load and flexible operation of unmanned aerial vehicles were combined. An automatic leveling control system was designed to keep the spray boom level during spraying operation. Firstly, the automatic leveling control system was identified and modeled. The research of automatic leveling control algorithm of rotors hovering spray boom was carried out by using the method of “gyroscope and lidar”. It included simulation test, bench test and field test. The experimental results showed that the fuzzy PID control algorithm based on the fusion of two sensors was better than the angle PID control algorithm based on the single sensor. It can avoid instability state better. In the field test, when the spray boom entered the stable state, the average height of each point above the ground of the whole spray boom was ranged from 1.4m to 1.5m, and the maximum standard deviation was 0.1027m. The variation coefficient of the mean height of each point of the spray boom collected at 10 different moments was 1.40%, indicating that the hovering height of the spray boom was stable. The research verified the feasibility of the rotors hovering spray boom and provided reference for the prototype development of the rotors hovering spray boom sprayer.