Abstract: The fracture reason of the forklift mast was analyzed by means of chemical composition analysis, mechanical property testing, metallographic examination, fracture analysis and so on. The results showed that the pit defect and cracks existed in weld crater parts of the mast, the pit defect and cracks formed notch effect and stress concentration. Furthermore, the mast worked under the asymmetric stress, at last the fatigue fracture occurred in mast.