Abstract: Aimed at have some petioles in threshing, experimental studies on connection forces between grain and petiole, petiole and branch, branch and caulis, with special clamp on the testing equipment of agricultural material, were carried out. The testing results show that the breed, position and the force of direction all have effects on the connection force and the effect of the force of direction is the most significant. The connecting force is higher following the axes direction and lower in the contrary direction. Analysis shows that the percentages of petiolated grains are lower when the hit force follows the axes direction of spike in mechanical threshing.