In order to solve the problem of the seeding quality descend caused by the poor performance of the dibbler, a secondary seed feeding mechanism was added between the seed taking plate and the duck’s beak. The purpose was to improve the seeding performance by planning the seed movement path, reducing the height of seed point, and reducing the phenomenon of missing and replaying. On the basis of the air suction roller type dibbler, the installation position, seed path contour, entrance and exit structural parameters of the secondary seed feeding mechanism were designed and analyzed. The trajectory, velocity and seeding performance of seeds were discussed by discrete element method. The causes of the phenomenon of missing and replaying were clarified. And the evaluation index of seeding performance of secondary seed feeding mechanism was determined as follows: qualified index, missing index and replaying index. Three factors quadratic rotation orthogonal combination test was carried out to study the influence of installation angle, operating speed and inner seed channel height on seeding performance. The results showed that the installation angle had a great influence on the seeding performance, the height of inner seeding channel had the least influence on the pass index. When the installation angle was 10.95°, the operating speed was 3.29km/h, and the height of inner seed channel was 16.68mm, the qualified index was 98.40%, the missing index was 0.85%, and the replaying index was 0.75%. Field experiments were carried out, the qualified index of the dibbler with the optimized secondary seed feeding mechanism was 98.06%, which was 2.21 percentage points higher than that of ordinary dibbler.