The utility model relates to a cable fault testing device, its characterized in that: the apron is connected with protecting sheathing's right side by the hinge, laps and protecting sheathing component box, and there is the gyro wheel the outer bottom of protecting sheathing casing, and apron and protecting sheathing inner wall coat and be stamped the insulating layer, protecting sheathing casing inside bottom padded with blotter, and it is cotton that the interior four sides of protecting sheathing casing is the buffering, and on alternating current power supply placed the blotter in protecting sheathing, the capacitance loop of two control rod bottoms was connected with alternating current power supply by the interchange wire, and the structure of capacitance loop is the semicircular sheetmetal, and connected with response wire is equipped with ampere meter, ampere meter lower extreme series connection security resistance between right side capacitance loop and the interchange wire on the response wire. It can detect out the position that the cable breaks off by the accurate, and the solution has the complicated problem of device detection streamer operation now, and then the efficiency of improvement detection, and installs the influence that receives the outage as the solitary whole will not of one.