Abstract: For reducing mechanical damage of corn seed in the process of threshing and mastering breaking mechanism of kernel stem of corn seed, the breaking properties of single kernel stem of corn seed under various varieties and various inflicting force manners and various moisture content were analyzed in this paper. Experimental researches show that resisting pressing intensity and resisting cutting intensity will decrease with the increase of kernel moisture content, however resisting bending intensity and resisting pulling intensity will increase with the increase of kernel moisture content; the separating manner of press has a largest impact on breaking force of kernel stem and the separating manner of cutting force has a least impact on breaking force of kernel stem; under the same separating manner, the separating properties of corn seed of different varieties were different. It contributes to provide a foundation for the choice of threshing component and the design of threshing system with little damage.