Abstract: Abstract: Precision planting is the advanced technology that sows seeds in the predetermined position of soil accurately and quantitatively by precision planter. Precision seed-metering device is the key component of precision planter and its seeding performance directly affects the quality of rice sowing, which divided into two types according to the working principle. The one is the mechanical metering device, and the other type is the pneumatic seed-metering device. The hole-wheel precision seed-metering device is a kind of mechanical seed-metering device and its seed-filling performance directly affects the seeding quality, which has been increasingly widespread due to its advantages of high planting quality when sowing rice seeds. But it has disadvantages of bad uniformity not to meet the seeding requirement of different size rice seeds. There are many dry direct seeding varieties rice and the sizes of their seeds are different. The adaptability of the seed-metering device to different sizes rice seeds is different. High speed work will also have a great influence on the seed-filling of the seed-metering device. For the problems of poor adaptability and low precision of the current rice drought direct seeding machine, a slide hole-wheel seed-metering device was designed to improve the direct seeding performance for rice. The sphericity was selected as the indicator of 3-dimension size of rice seeds. According to the simulation test by EDEM software for seeding process in 3 varieties of rice seeds with different sphericity (Gangyou 898, Guofeng No.1 and Gangyou 3551) under 6 seed-metering device rotational speeds, the changing laws of seeding performance of rice seeds with different sphericity under different rotational speeds were obtained and the influences of rotational speeds and seed sphericity on seeding performance were analyzed. The simulation results showed that the seeding performance of rice seeds of Gangyou 898 was better than other 2 varieties of rice seeds when the rotational speed of seeding wheel was between 15 to 40 r/min, when the rotational speed of seeding wheel was between 15 to 30 r/min, the seeding qualified rate of those 3 varieties rice seeds floated between 84.01% to 87.91%, and the seeding qualified rate had a increasing trend of overall presentation as the rotational speed of seeding wheel increases, when the rotational speed of seeding wheel was faster than 30 r/min, the seeding qualified rate declined significantly with the increasing of rotational speed. 5 varieties of rice seeds with different sphericity (Guofeng No.1, Liangyou 628, Gangyou 898, Gangfeng 188 and Gangyou 3551) were selected as experimental materials. The rotational speeds of seeding wheel and seed sphericity were selected as influence factors, and seeding qualified rate, missing rate and replay rate were taken as evaluation standards. The bench test was done with the quadratic regression orthogonal combination design method. The regression equation and response surface between the performance index and the rotational speed and seed sphericity were acquired to verify the simulation results after analyzing those data by Design-Expert 8.0.6 software. Finally, the optimal parameter combination was obtained through the regression equation: the rotational speed of seeding wheel was 27.12 r/min and seed sphericity was 44.61%. In this case, the qualified rate is 83.90%, the missing rate is 5.43% and the replay rate is 10.67%, which is the best seeding performance for the seed-metering devices. The results from bench test were in accordance with that from simulation. The changing trends of seeding performance in bench test with rotational speed and seed sphericity were also basically consistent with that in simulation experiments. The field test result showed that, when the average rotational speed was 27.12 r/min and the forward velocity was 5.85 km/h, the seeding performance of seed-metering device could meet the requirements of precision sowing for all size grades of rice seeds. The research results provide a reference for structure optimization and performance improvement of slide hole-wheel precision seed-metering device.