The invention relates to a tool capable of replacing 500KV straight-line single-connection double-string horizontal insulator. The tool comprises a double-connection turning board card, adjustable insulation pulling rods, and four-wire hooks which constitute a bearing mechanism. The tool is characterized in that the double-connection turning board card is formed by rotatably connecting a card body and a turning board by a rotating shaft to form a whole body, and after the card body and the turning board are integrated, the matched corresponding parts of the card body and the turning board form a card clamp; hanging boards are connected to both ends of the double-connection turning board card by screws, and a pin hole is formed in the middle of the double-connection turning board card; the lower ends of the hanging boards are in threaded connection with the insulation pulling rods; the lower ends of the insulation pulling rods are in threaded connection with screws of the four-wire hooks; a clamping hook for holding wires is arranged at the upper part of each of both ends of each four-wire hook main body, a wire hook is fixed at the lower end of each of both ends of each four-wire hook main body, a screw hole is formed in the middle of each four-wire hook main body and a worm and gear is fixedly mounted below each four-wire hook main body. By virtue of the tool, insulator strings with different models and different lengths can be replaced; compared with a current tool, the tool has the advantages that the number of work tools is effectively reduced, the labor intensity is reduced, the work efficiency is improved, and the replacement of broken or zero-resistance insulators can be replaced more safely, conveniently and quickly and with a higher labor-saving effect.