The orthogonal test and finite element (FE) ANSYS software were used to analyze the influence of rat tooth's rake angle, apex angle and tooth root fillet on the stress strain of saw blade. The influence of tooth root fillet on all kinds of maximum stress was analyzed. The results show that the influence of rake angle, apex angle and tooth root fillet on the strain of saw blade is very small. The radius of tooth root fillet is the largest influence relatively of maximum radial compressive stress, tangential tensile stress and maximum Von Mises stress, and apex angle's influence is at minimum relatively. Apex angle is the largest influence relatively of maximum radial tensile stress and tangential compressive stress, and rake angle's influence is at minimum relatively. The optimal range of radius of tooth root fillet is obtained, at the same time, the maximum Von Mises stress distribution characteristics is found.