Abstract: Fracture of 45 steel forged shackle occurred during service. Comparative analysis of fractured and non-fractured shackles was carried out through chemical composition analysis, fracture analysis, metallographic examination, mechanical property testing and so on. The results show that surface microcracks and coarse microstructure caused by forge overheating were the reasons for fracture of shackle, which reduced loading capacity and plastic deformation capacity of the shackle. Under the external force, the cracks expanded continuously and ultimately led to brittle fracture.