Abstract: In order to analyze the cause of fracture in the use of 05Cr17Ni4Cu4Nb stainless steel tie rod, taking the broken05Cr17Ni4Cu4N b stainless steel tie rod as the material, the mechanical properties, chemi cal composition, metallographic microstructure and fracture morphology were tested and analyzed. The results show that the fracture property of the tie rod is overload brittle fracture, and the elongation and section shrinkage after fracture are not qualified. The main reason for fracture is the high solid solution temperature during heat treatment, and the large amount of ferrite precipitates along grain boundaries and within grains, which result in the increase of brittleness of the parts and the deerease of shear resistance then the fracture appears.