The invention provides a secondary loop wire core protection sleeve. When the secondary loop wire core protection sleeve is applied to secondary loop wire disassembly and assembly, the insulation protection of a wire core is realized. The secondary loop wire core protection sleeve comprises a first shell, a second shell, an inflating and deflating assembly, an air bag, a sealing rod and a pendulum rod. The first shell comprises a first wire core clamp, a first mark number clamp plate, a second wire core clamp plate and a first conductive wire clamp plate which are sequentially arranged and are mutually connected. The second shell comprises a third wire core clamp plate, a second mark number clamp plate, a fourth wire core clamp plate and a second conductive wire clamp which are sequentially arranged and are mutually connected. The connection end of the first conductive wire clamp plate and the second conductive wire clamp plate are hinged and connected. The inner walls of the first, second, third and fourth wire core clamp plates are provided with semi-circular sealing pieces. The inner wall of the first mark number clamp plate is provided with the air bag. The opening end of the air bag communicates with a convex inner cavity. The first mark number clamp plate is provided with the inflating and deflating assembly. According to the protection sleeve, the insulation protection of the wire core can be effectively realized, and the protection sleeve can be reused.