Structural type of distributor normally dominates the uniform fertilizing quantity in each row and the damage rate in the fertilizing process under wide and high-speed sowing and synchronous fertilization of air-assisted planter for rapeseed and wheat. In this study, the main structural parameters of the distributor were determined according to the optimal fertilizing performance in an air-assisted applicator. The distributors with the flat top type, the inverted cone installed on the flat top type, the dome type, and the inverted cone installed on the dome type were taken as the research objects. The initial structural parameters were set: The inner diameter of delivering fertilizer tube was 82 mm. The length, width, and height of the diversion fertilizer outlet were all 30 mm. The diameter of the upper covering plate was 130 mm. The cone angle was 80° and the height of the inverted cone was 50 mm. An elastic collision model was established between the pelletized fertilizer and the main part of the distributor using Hertz theory. A Discrete Element Method (DEM) coupled with the Computational Fluid Dynamics (CFD) was selected to analyze the effects of 4-type distributors on the motion characteristics and fertilizing performance of fertilizer particles. The simulation results showed that the average values of maximum velocity and collision normal force, and the uniformity variation coefficient of each row fertilizing quantity of fertilizer particles in the distributor devices of the dome type, the flat top type, the inverted cone installed on the flat top type, and the inverted cone installed on the dome type all increased gradually. The maximum collision normal forces of fertilizer particles in the distributor of the dome type, the flat top type, the inverted cone installed on the flat top type, and the inverted cone installed on the dome type were 43.08, 62.50, 70.66, and 116.15 N, respectively, where the proportions of maximum collision normal force greater than 30 N (referring to the damage force range of pelletized fertilizer were 1.56%, 3.33%, 6.67%, and 38.89%, respectively). Furthermore, the maximum velocities of fertilizer particles in four-type distributors were 26.32, 29.14, 33.66, and 36.1 m/s, respectively, where the proportions of maximum velocity greater than 25 m/s were 0.44%, 7.78%, 9.33%, and 22.16%, respectively. The dome type distributor presented the minimum values in the maximum velocity, while the proportion of maximum velocity was greater than 25 m/s, indicating a small change in the velocity of fertilizer particles for the stable transportation of fertilizer particles. An intelligent test platform was used for planting machines to verify the fertilizing performance of an air-assisted fertilizer. The bench results indicated that there was highly consistent with the experimental and simulated changes in the maximum velocity and the maximum collision normal force of fertilizer particles in the distributor with different structural types. In a dome type distributor, the variation coefficient of uniformity in each row fertilizing quantity of particles was in the range of 6.35% to 7.52%, while the variation coefficient of stability in total fertilizing quantity was in the range of 1.53% to 1.92%, and the damage rate was in the range of 2.97% to 3.26%. Correspondingly, the dome type distributor achieved a better fertilizing performance than others. The findings can provide a sound reference to improve the structure of the distributor for precision fertilizing.