The invention relates to a high-voltage, ultrahigh-voltage and extra-high voltage switch transfer current device for busbar transfer load current operation. The high-voltage switch transfer current device comprises a horizontally arranged vacuum switch, a switch operating box and a steering square box between the horizontally arranged vacuum switch and the switch operating box, wherein a fixed contact and a moving contact of the vacuum switch are coaxially arranged opposite to each other in a shielding case of a vacuum arc extinction chamber, a plurality of thread grooves are arranged on a columnar contact of the fixed contact from the columnar face to the end face of the contact at equal intervals, and the contact end of the moving contact is provided with a slot matched with the columnar contact of the fixed contact; a brake separating spring crank arm, a braking crank arm and a roller crank arm are arranged on a control main shaft of an operating mechanism of the switch operating box. By the technical scheme, an isolating switch is endowed with the capability of switching on and off busbar transfer current during double-busbar changeover operation, and thus, the technical purpose that power-frequency low-voltage great-current transfer current arcs produced in the busbar transfer can be switched on and off by the moving contact and the fixed contact of a 100-1100 KV outdoor AC high-voltage isolating switch can be achived.