The utility model relates to a clamping tool applicable for measurement on the oil level in an oil-charging porcelain bushing of an electric system. The clamping tool comprises an insulating vertical rod, a lifting motor, a hinge seat, a transverse connecting rod, a connecting rod jackscrew, a connecting rod telescopic motor, a telescopic rod, a clamping sleeve, an installation seat, a rotating shaft, a double-clamping-arm clamp, a clamp jackscrew, a handle clamp telescopic motor, a screw rod and a clamping motor, wherein the lifting motor is arranged in the middle of the insulating vertical rod; the hinge seat is arranged on the top end of the insulating vertical rod; the transverse connecting rod is installed on the hinge seat in a hinging way; the connecting rod telescopic motor is installed on the connecting rod; the telescopic rod is connected with the shaft end of the connecting rod telescopic motor; the clamping sleeve is arranged on the end of the telescopic rod; the installation seat is installed on the lower part of the insulating vertical rod; the rotating shaft is installed on the installation seat in a penetration way; the double-clamping-arm clamp is sheathed on the rotating shaft; the handle clamp telescopic motor is arranged on a handle of the double-clamping-arm clamp; the screw rod is installed on the root of the double-clamping-arm clamp in a penetration way; the clamping motor is connected with one end of the screw rod. The clamping tool is rational in design, scientific in structure, convenient to use and capable of avoiding an instrument from sliding and guaranteeing the favorable completion of a test.