This paper presents a new measure to eliminate the ground current for fault location of power cable and analyses the basic principle of inversion bridge method.Before using the inversion bridge method for fault location, switch-on a circuit combined with resistances and direct-current source, the ground current can be completely eliminated by adjusting the resistance value.The paper analyses the eliminating measure circuit principle, sets out the deducing process, and sets up a model experiment to test the validity of the measure.