The invention discloses a protection device used for a high-voltage region of an electric power test. The device comprises a master control device and a plurality of fence devices, each fence device comprises a cylinder housing, a signal light emission unit and a signal light reception unit, a cylinder body of the cylindrical housing is distributed with a plurality of sliding belts around the cylinder body from top to bottom, the sliding belts are circumferential belts with belt-shaped slots on the cylinder body of the cylindrical housing, signal light emission ports and signal light receptionports are distributed in the slots, and the signal light emission ports and the signal light reception ports are both matched with the slots and slide in the belt-shaped slots. The substantial effects of the device are that the fence devices whose cylindrical housings are distributed with the plurality of sliding belts from top to bottom are adopted, and the signal light emission ports and the emission light reception ports are arranged in the sliding belts so that stereoscopic high-voltage test protection regions of different heights are formed; besides, a long-period optical fiber grating is adopted as a pressure detection device of a sensor so that the reliability and the sensitivity of the protection device of the electric power test region can be improved.