Bugarin has studied two shafts and found that a larger-size fillet can minimize stress concentration in the dangerous sections which shows that the fatigue life can be significantly increased with a simple change in the structural details. Because the fracture failure of the crankshaft can affect the normal work of the machine, the failure analysis of crankshaft have a very important theoretical and practical significance. This paper finds out the cause of the crankshaft fracture through the failure analysis of
the crankshaft (Fig. 1), so as to guide the design and production, improve the fatigue strength and the work reliability of the crankshaft.