Abstract: In order to solve the problems of uneven fertilizer distribution, low efficiency, and high labor intensity in the process of rice fertilization, a device and control system of pneumatic fertilization in the rice field was designed in this paper. The pneumatic conveying method is adopted to realize the conveying of fertilizer. The driving speed of the machine and the speed of the fertilizer discharging motor are matched in real-time through the electronically controlled fertilizer discharging system. Finally, the purpose of precise fertilization is achieved. Through the flow field analysis of the designed Venturi tube mixing cavity, the optimal mixing cavity diameter of 15 mm is determined. The field experiment was carried out, and the results showed that the coefficient of variation of average fertilizer discharge of each row was less than 2.21% within the range of motor speed, the consistency of fertilizer discharge of each row was good, and the fertilizer discharge was stable. The deviation of the fertilization rate in each area was controlled within 7.47%, and the fertilization accuracy was better with the target fertilization rate at 150 kg/hm~2 and the operating speed at 4 km/h. The lag time of fertilizer in the discharge pipe increased with the increase of the length of the fertilizer discharge pipe, and the variation range was 0.67-1.81 s. It is proved that the pneumatic fertilizer device designed in this paper can meet the production demand.