Abstract: In recent years,faults of the outer sheath of high-voltage single core cables have occurred frequently,which seriously affecting the safe and stable operation of the power system.This paper analyzes an abnormal grounding current fault of the outer sheath of a 220 kV power cable,analyzes the trend of changes in the grounding current of the metal sheath of the cable after the outer sheath is damaged,and its impact on the insulation performance of the cable body. The paper also provides methods for finding the outer sheath fault,repair solutions,and subsequent operation and maintenance suggestions,which provides reference for the subsequent operation and maintenance of high-voltage single core cables.