Isolating switch of on-load tap-changer

The invention provides an isolating switch of an on-load tap-changer. The isolating switch comprises: a switch shell; a shifting fork rotating shaft arranged in the switch shell; four static contacts; a switch shifting fork, wherein one end of the switch shifting fork is rotatably arranged on the shifting fork rotating shaft, and the other end of the switch shifting fork is provided with a moving contact; and a dead point spring, wherein the first end of the dead point spring is connected with the switch shell, and the second end of the dead point spring is connected with the switch shifting fork. Parts of parts of the isolating switch are loaded through the switch shell, so that the isolating switch serves as an integral switch structure and serves as an independent component to be installed and designed; the switch shifting fork is rotatably connected to the shifting fork rotating shaft, so that the switch shifting fork swings and drives the moving contact to be in switching contact with the two columns of static contacts, and the transition on-off time sequence of the vacuum envelope is controlled; and meanwhile, the dead point position of the dead point spring is arranged between two static positions where the moving contact is contacted with the two columns of static contacts, so that stable and compact contact between the moving contact and the two columns of static contacts is ensured, and the electrical characteristic is reliable.