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In order to meet the needs of corn breeding test, an air-suction precision seed meter with self-clearing seed chamber was designed, whose seed chamber and seed clearing chamber were independent of each other. The process of metering and clearing did not interfere with each other. The self-purification rate could achieve 100%. The shape of breeding seeds was analyzed, and the key structural parameters of seed meter were determined according to the characteristics of breeding experiment. Dynamics analysis of the process of seed adsorption was carried out, and EDEM software was used to verify the disturbance of churn plate to the fewer population. Fluent software was used to simulate the seed clearing process. It was proved that when the remaining seeds were not more than 10 and the clearing time was not more than 1s, the vacuum of clearing seeds was greater than 3kPa, the remaining seeds could be cleared completely. Seeds used in breeding experiments were graded, single factor experiments were carried out in the vacuum range of 3~4kPa. The results showed that seeds adsorbed on suction holes in the clearing stage could still be sown normally regardless of their specifications. Experiments of the normal seeding stage were carried out on the JPS-12 test bench. When the vacuum was between 6kPa and 8kPa, the operation speed of the seeder was less than 3.6km/h, and the working face of the scraper was within 2~4mm from the suction hole center, the qualified index of seed spacing exceeded 95%, the missing-seeding rate and the reseeding rate were less than 1% and 4%, respectively. Each index met the national standard. The performance of seed metering device was effective while the clearance rate could reach 100%. The field experiment of seeder proved that the seedling emergence effect met the seeding requirement of breeding experiment. 