In order to solve the problem of low single seed rate caused by air-suction roller dibbler for peanut decreases due to the unstable performance of the first seed feeding, the seed separation tray was added between the seed collecting tray and the secondary seed feeding mechanism of the air-suction roller dibbler for peanut. The seeds were limited in a small tooth shaped space, and the seeds were moved along a predetermined track to improve the accuracy and precision of seed delivery of the air-suction roller dibbler for peanut. The tooth shape of seed separation tray and the position relationship between seed separation tray and seed collecting tray were designed and analyzed, and the structure and position parameters of seed separation tray were determined. The working process of air-suction roller dibbler for peanut was studied, the movement track of seeds in seed carrying area was analyzed, and the mechanism of missed seeding and replanting was clarified by using DEM-CFD coupling method. Three factors quadratic rotation orthogonal combination test was conducted with qualification index, missed seeding index and replaying index as evaluation indexes. The effects of tooth shape direction angle, installation angle and operation speed on seed delivery performance were analyzed. The results showed that when the direction angle of the tooth shape was -4.55°, the installation angle was 14.99° and the operating speed was 4.01km/h, the seed metering performance of the air-suction roller dibbler for peanut was the best. The qualification index was 94.99%, the missed seeding index was 2.49%, and the replanting index was 2.52%. Based on the optimal combination, the field contrast test was conducted, and the test results met the technical requirements of single seed precision sowing machine for peanut.