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Aiming at the problems of poor seed-filling performance and seeds were easily stuck in the seeding wheels of metering device for small particle size seeds，seeding wheels with inclined parabolic holes and stirring structure were designed which could plant 2±1 seeds of rapeseed sesame and pakchoi in one hole. Mechanical models for seed-filling and seed-casting were constructed. The range of main structural parameters of seeding wheels and how the parameters influence on seed-filling and seed-casting were analyzed, based on the mechanical and physical properties and precision hole-seeding requirements of rapeseed sesame and pakchoi. The influence of the main structural parameters on seed-filling was verified by using EDEM software, and high-speed camera. The optimal value of distance from parabolic vertex to circular center, focal distance, parabolic tilt angle, width coefficient, side tilt angle and churning structure height were determined. The critical conditions for avoiding seeds stuck in holes or dragged by churning structure were determined. The empirical formulas for calculating the optimal structure parameters by physical properties of seeds were presented. The JPS-12 test-bed was used to study the seeding performance of seeding wheels with the optimal structure for Huayouza 62, Hangtianxinzhi T31-8 and Wuyueman. The qualified rates of seeds per hole were 92.00%, 90.00% and 90.67%, and the qualified rates of hole spacing were 83.67%, 81.83% and 82.50%, respectively. Field tests showed that the average number of Huayouza 62 seedlings per hole was 1.16, the qualified rate of 2±1 seedlings per hole was 89.67%, and the qualified rate of hole spacing was 81.54%;the average number of Hangtianxinzhi T31-8 seedlings per hole was 1.15, the qualified rate of 2±1 seedlings per hole was 85.77%, and the qualified rate of hole spacing was 75.51%. The metering device could meet the requirements of precision hole-seeding for rapeseed and sesame. The research result can provide a reference for the design and research of seeding wheels of metering device for small particle size seeds.