Abstract: This paper introduces the vibration characteristics of abnormal low-frequency vibration of low-pressure rotor of a 60Hz unit, and analyzes that the cause of abnormal vibration is caused by poor lubrication. After inspection, it is confirmed that the local bearing load is too heavy due to maintenance, and the poor lubrication is caused by the fragmentation of rolled tungsten. The research of this paper has reference significance for the analysis, treatment and prevention of similar low-frequency vibration faults of subsequent operating units.