To solve the problem of a mining triaxial heavy-duty dump’s putting rod ruptures prematurely, When the dump in the bending and twisting conditions, the push rod’s static strength and stiffness was analysed by Hypermesh, and get the modals shapes and modal frequencies and generated a frame MNF file (modal neutral file) from the Ansys, established the rigid - flexible coupling model of the frame in ADAMS, get a load time history of fully loaded front and rear suspension. According to material fatigue properties’ S-N curve of the frame, using of MSC. Fatigue software the frame’s life was analyzed. The result showed the position of minimum fatigue life of frame is consistent to the position of abnormal rupture of putting rod in actual use; in order to improve the design of heavy-duty dump truck provides a reference.