Abstract: The fracture failure of the adjust stud in metro pantograph happened during runtime, the fracture reasons of the adjust stud in metro pantograph were analyzed by means of chemical composition analysis, fracture macro and micro analysis, metallographic examination, mechanical property test and so on. The results show that the surface of threaded connection pair at the end of the nut was worn and corroded during runtime, and the adjust stud was subjected to alternating bending load, which resulted in corrosion fatigue fracture of the stud.