The invention discloses a special device for replacing an HGIS isolation switch buffer. The special device comprises an isolation switch transmission device and a double-cushion-block clamping part, wherein the isolation switch transmission device comprises two connecting rods, a balance spring and a triangular connecting lever, the two connecting rods are connected by virtue of the triangular connecting lever, the triangular connecting lever is connected to the balance spring, the double-cushion-block clamping part is arranged between the triangular connecting lever and the balance spring, the double-cushion-block clamping part comprises two supporting plates and two connection bolts, the bolt hole is formed in each supporting plate, the connection bolts penetrate through the bolt holes, the bolt holes are formed in two ends of each supporting plate, each supporting plate is an insulation rectangular block, and a groove is formed in each supporting plate. The special device is convenient to carry, detachable and capable of solving the problems that the overhaul time is too long when the personnel enter a gas chamber to work, also has a function of saving the manpower and material resources and improves the working efficiency.