The increase of grain production is inseparable from fertilization. However, the side effects like energy waste, environment pollution and economic loss are largely caused by unreasonable fertilization. The characteristics of traditional fertilization machine are low operation speed, small fertilizer width and low efficiency, which also followed with unbalanced fertilization in each row, and a large amount of fertilizer is inefficiently utilized. Studies have shown that rational fertilization, especially mechanized precision proportionate fertilization can significantly improve the quality of agricultural products. In order to realize highspeed and widewidth fertilization operation, rapid quantitative transportation of granular fertilizers and proportionate fertilization in each row of the field fertilization machine, the pneumatic centralized fertilization seeder has become the main research and application machine. In order to study the movement characteristics of fertilizer particle in the pneumatic centralized fertilizer distribution device, the airsolid twophase flow characteristics in the pneumatic centralized fertilizer distribution device were numerically analyzed by the coupled simulation of discrete element method (DEM) and computational fluid dynamics (CFD). In this coupling model, solid fertilizer particles were simulated by EDEM software and the air phase was operated by Fluent software. The optimum structure parameters of the fertilizer distribution device were determined by studying the effects of the cone angle of the screwing caps and the diameter of bellows on the air pressure, air velocity and motion characteristics of fertilizer particle. Based on this structure, the distribution uniformity of the fertilizer distribution device influenced by the inlet air velocity and fertilization velocity were studied. The simulation and test results showed that the air flow and the fertilizer particle had the best fluidity and uniformity in the fertilizer distribution device with the taper angle of the screwing caps of 120° and the diameter of the bellows of 80mm. Under the conditions of 25~35m/s inlet air velocity and 0.26~0.44kg/s fertilization velocity, the coefficient of variation of fertilization amount on each row was not more than 4.9%. The distribution accuracy and uniformity of different kinds of fertilizers were also met the requirements of fertilization operation.