Abstract: Abstract: The planting area of rice is about 30 million hectares each year, of which japonica rice is close to 9 million hectares mainly planted in Heilongjiang, Jilin, Liaoning and Jiangsu provinces. With the increasing demand for high-quality milled rice, japonica rice planting areas and total yields increased rapidly in recent years. Nursery transplanting is the mainly used planting pattern for japonica rice, and it has been proved that cultivating more tillers and strong seedlings is one of the key measures for improving good quality and high yield for japonica rice. In order to cultivate strong seedlings suitable for mechanical-planting, a large number of precision seeding machines, which have more uniform seeds distribution and better growing area for per seed, had been developed by researchers all over the world. Among various precision seeders, those utilizing air-suction metering devices were researched and used most widely, but problems occurred with the suction holes easily to be blocked and hardly to be cleaned. Based on the directional precision seeding device for japonica rice, in order to further stabilize the seeding performance and enhance working efficiency of the device in low seeding rate, a centrifugal supplying seeds mechanism was designed which was primary composed of seeds box, a horizontal turnplate with guide cone and a conical flow divider with V-shape grooves, etc. The simulation model of japonica rice particle and the mechanism were established using Solidworks software in order to determine performance parameters of the supplying seeds mechanism, and supplying seeds performance simulation of the mechanism was carried out by EDEM software. The relationships between supplying seeds performance and turnplate diameter, rotation speed and inlet opening were studied and analyzed, respectively. The simulation results indicated that the inlet opening and turnplate rotation speed had significant effect on seeds dispersion degree and supplying seeds performance, which the total flow rate increased in linear with increasing of the inlet opening and turnplate rotation speed, and variability coefficient of flow rate among all exits first decreased and then increased. The turnplate diameter had an effect on supplying seeds performance but not obvious, then the total flow rate decreased with the turnplate diameter increasing, and variability coefficient of flow rate among all exits approached to the lowest value 14.37% and change was stable within 200 mm to 220 mm of the turnplate diameter. With lower variability coefficient of flow rate among all exits as the key point, and taking requirement of total flow rate of the supplying mechanism into consideration, the smaller was the variability coefficient of flow rate among all exits, and the lower was the total flow rate. The turnplate diameter was 220 mm, the turnplate rotation speed was 80 r/min and the inlet opening was 10 mm, which was selected as an ideal combination; its simulation total flow rate was 263 grains/s, and variability coefficient of flow rate among all exits was 14.37%. Under the same condition, Longjing26 rice grains were selected and the bench test was performed. The test results indicated that the total flow rate was 276 grains/s, and the variability coefficient of flow rate among all exits was 15.56%. In comparison with the simulation results, the error of the total flow rate and the variability coefficient of flow rate among all exits were 13 grains/s and 1.19%, respectively. The test results fit well with the simulation results. The experimental comparison of seeding performance had been carried out, and the results showed that the directional precision seeding device after increasing the design of supplying mechanism worked more reliable and working efficiency increased by 25%. The research can provide a reference for performance improvement of the directional precision seeding device for japonica rice.