The present invention relates to a single-core power cable jacket art ground fault detection, fault detection and particularly to a system and method for single-core power cable sheathing based on the measured ground loops, the grounded for a single, cross-connects and doubly terminated to ground under three cable sheath for grounding loop detection, the transformation of a variety of first cable grounded tank for installation of each switching element such grounding can easily and safely be converted to a single-ended mode in the measurement, and then this lower sheathing circulation state measurement values obtained circulation characteristics at different locations ground fault according to the theoretical model and experimental data circuit fault loop circulation jacket grounded at a single mode, further determination and fault locating, the entire detection process is simple, a small amount of calculation can be on line.