Abstract: In recent years, grounding system defects have become one of the main causes of high voltage cable fault trips, especially the corrosion, cracking, and falling off of lead sealing at cable terminals or joints, which cause poor grounding defects of the cable metal sheath. By introducing an abnormal defect in the grounding circuit resistance detection value of a 220 kV high voltage cable using cross-interconnection grounding method, the equivalent circuit model of high voltage cables is elaborated in detail. Starting from the fault mechanism, it deeply analyzes the impact of poor grounding defects on the safe operation of cables and the urgency of defect elimination. It also introduces the basic principle of grounding circuit resistance detection of the cross-interconnection system in detail. In response to the insufficient defect positioning ability of this detection method, it is proposed to combine the shunt comparison method and the “window opening” detection method to carry out defect search and positioning. The defect is finally located at the lead sealing position of the cable terminal tail pipe of Tower No. 15, which supports the operation and maintenance personnel to carry out targeted maintenance and defect elimination. Finally, in view of the resistance defects of cable grounding circuit and the quality control of lead sealing process, relevant preventive measures and suggestions are put forward.