Abstract: The material and mechanical properties of Jimusar white skin garlic and Ili purple skin garlic in Xinjiang were studied to provide theoretical basis for garlic grading and garlic precision seeder optimization. The shape size, center of gravity, mechanical characteristics of different moisture content and loading speed, and maximum friction with different contact materials of garlic seeds were measured. The outer size of garlic was analyzed by quadratic regression. The thickness and length of Jimusar white and Ili purple garlic were taken as the standard for grading. The proportion of Jimusar white skin and Ili purple skin garlic with lower gravity center was 71% and 81% respectively. Moisture content and loading speed have significant effects on the crushing force. The higher the moisture content, the smaller the crushing force; the higher the loading speed, the greater the crushing force. The maximum friction angle of garlic seeds on the contact surface of acrylic, plexiglass and stainless steel increased in turn. In order to improve the single seed rate of spoon chain type seed picker, the thickness and length should be given priority in the size grading of Jimusar white skin and Ili purple skin garlic. The closer the center of gravity to the garlic root, the higher the sprouting rate after the garlic is sown. In order to ensure the transportation of garlic seeds and the sprouting rate after sown, the extrusion pressure on garlic seeds should not exceed 55.1 N. The inclination angle of the seed metering box should be greater than the maximum friction angle of the two varieties to increase the single grain rate of the metering.