Abstract: In the fault of high voltage power cable, a large number of erosion phenomenon of cable buffer layer is found. This erosion is accompanied by an increase in temperature due to concentration of capacitance current. In this paper, based on the grounding mode of cable line, through theoretical calculation and simulation test of cable structure sample, the change of capacitance current distribution on the surface of buffer layer under wrinkle aluminum sheath was understood, the test datas were analyzed, and the reason of erosion was found out to provide fault analysis means for cable operation and inspection.