Abstract: The fertilization in seedling stage is an important link in paddy production, which plays an important role in ensuring the high yield of rice. The traditional way of fertilizing is manual fertilization of high labor intensity. Granular fertilizers are the most common type of agricultural fertilizer, since they are easily produced, transported, and applied. In order to be effective, however, granular fertilizers must be properly handled and distributed. However, manual fertilization has several disadvantages, such as heavy labor intensity, poor uniformity, and so on. The poor uniformity will easily lead to the uneven growth of rice in the same region, thus impacting the rice yield. Therefore, in the process of rice production, mechanization of fertilization is badly in need of solving these problems. A centrifugal distributor is a kind of fertilizer applicator used generally at present. The principle is spreading out the fertilizer using centrifugal force by the output shaft driving the rotary distributor disk. The distributor's mechanism adopts a disc type. The configuration is divided into single disc and opposed-double disc. The relative theoretical research is conducted on the assumption that the distributor plate is not conical and the blade is particle. The theoretical research plays a key role in further optimizing the granular fertilizer spreader. The traditional centrifugal fertilizing machine is used in order to make sure that the fertilizer can be spread out smoothly from the disc. Usually 2 ~ 4 vanes are arranged on the disc. The shape of the blade could be straight or curved. The blade installations should be radial type, forward type, and backward type. A centrifugal spreader is currently widely used, and one of the most common granular fertilizer application devices is the spinner spreader. The spinner spreader consists of a rotating disc with vanes bolted to the disc surface. Fertilizer poured onto the spinner is thrown onto the ground after colliding with the rotating vanes. The chief advantages of the spinner spreader are that it has a large spread width, combined with small size. The performance of spinner spreaders has been widely investigated. These investigations have greatly increased our understanding of how to model the dynamics of particles distributed by a spinner spreader. This paper analyzes the mechanism performance of the cone disc spreader, and explores the motion and distribution characteristics of fertilizer in the process of fertilization, to provide a theoretical basis for the design of a rice seedlings and fertilizer machine. This study designed a cylindrical disk for the fertilization mechanism, composed by a disk body, guide rail, and the boss. The swing plate body is like a rotating parabolic. The rail track is an involute spiral, with triangular sections. The spreading process includes: fertilizer particles fall into the feed area under the impact of gravity; under the rotating force, the fertilizer particles then quickly gain the initial velocity and do accelerated motion along the involute spiral guide. The fertilizer particle has higher speed moving to the left edge of the disk and does a projectile motion in the air until the fertilizer particle falls to the ground to complete the spreading process. For the convenience of theoretical analysis, a single fertilizer particle is simplified into a rigid particle. The fertilizer granules were analyzed during the movement. The rotating disk's minimum speed can be determined. We analyzed the movement after the rejection, such as the motion time, throwing distance, and width. Theoretically, the fertilizer particles' feeding angle is equal to the throw angle on the swing disc spreader. The experiment is adopted to discuss the feeding area angle, the speed, and the impact of throwing disc height change on the rotating fertilizer law. The main factors affecting the left disc spreader's width are size and speed. The main factors influencing the left disc spreader's distance are the speed and height. The reasonable feeding angle is 75°, and the reasonable speed is 600 r/min.