Abstract:A critical negative pressure model of seed suction process of metering device was established with the principle of combined seeding with negative pressure suction and positive pressure injection to figure out the practical problems of sesame production including low efficiency of artificial planting,timeconsuming and high labor intensity of thinning and setting seedlings after emergence,and lack of suitable precision hole metering device. The different posture of seed suction and the contacting area between seed and pore was analyzed. The critical negative pressure of 14 seeds adsorbed by the hole was obtained with the multiobjective optimization method. The optimal hole diameter range of sesame precision hole sowing was determined to be 0.81.1 mm. The results of the image shooting test of the seed suction and transporting state showed that the different adsorption posture and probabilities of sesame was horizontal lying∶side lying∶upright ≈ 3.5∶ 1∶ 1. The variation of negative pressure required by different number of seed suction was consistent with the critical negative pressure model. The optimization test based on response surface was carried out to analyze the effects of the diameter of metering disc hole,rotation speed of seed metering device and negative pressure of air chamber on the seed metering performance including the rate of qualified number of seed in the hole,the rate of missed seeding and the rate of multiple seeding. The results showed that the rate of the qualified number of seeds in the hole,the rate of missing seeding,and the rate of multiple seeding was 96.04%,0.21%,and 3.75% when the diameter of metering disc hole,the negative pressure and vacuum degree of the air chamber,and the rotation speed of the metering shaft was 1.0 mm,-800 Pa,and 8.66 r/min,meeting the agronomic requirements of sesame planting. It will provide a reference for improving the structure of sesame precision hole seeding metering device.