To meet the agronomic requirements of maintaining the garlic clove upright with its root downward during the process of garlic planting,operating principles of rice transplanting mechanism was used as the optimal design basis of planting system of garlic planting machinery. Equations of cave width, space, depth were obtained through kinematic analysis. Mathematical optimization model was established with required cave width as objective function and restrained conditions not reported previously. Parameters affecting cave width were discussed, and optimized using Matlab. Optimization results indicated that the difference between desired and actual cave width was 0.02mm. Planting system of garlic planting machinery was simulated and analyzed using ADAMS. The results showed that the system met the garlic planting requirements.