The utility model belongs to the technical field of high-voltage AC isolation switches, in particular relates to a V-shaped cast steel base transmission device of an isolation switch. The transmission device comprises a base, a driving flange shaft, a driven flange shaft, a regulation crank, a regulation crank bracket, an inter-phase connection rod and an inter-electrode connection rod, wherein the base is an integral cast steel type structure, the regulation crank bracket is arranged in the middle of the front side of the base one end of the regulation crank is hinged with the regulation crank bracket, the other end is hinged with a regulation crank tie rod, the other end of the regulation crank tie rod extends to the back side of the base and hinges with the driving flange shaft, two ends of the regulation crank tie rods are provided with joint bearings, the inter-electrode connection rod is arranged above the regulation crank tie rod; the bearings are arranged on the base by bearing seats, frame oil seals are arranged on the bearing seats, two ends of the inter-phase connection rod and the inter-electrode connection rod are provided with positive screw joints and negative screw joints. The transmission device has the advantages of reasonable structure, a high strength of the base, stable transmission and high reliability.