Abstract: The bolt of an automobile air-conditioning compressor cracked during service, causing the leakage of air conditioning refrigerant. The failure cause of the bolt was analyzed by means of macroscopic morphology observation, SEM and EDS analysis, metallographic structure examination, chemical composition analysis and hardness testing. The results show that the flange surface of the bolt presents dendritic cracking, the fracture surface is dark gray, the fracture micromorphology is intergranular, the crystal surface is not clean and there is a local distribution of low melting-point tin among the grains. Due to the contact between the bolt flange surface and the low melting-point metal tin, and the high temperature in the working environment, the cracking by liquid metal embrittlement occurred under the tensile stress.