The invention discloses a vertical telescopic pneumatic high-voltage isolating switch. The isolating switch comprises a static contact, a post insulator, a conductive arm, a main conductive base and apneumatic mechanism part, wherein one end of the post insulator is provided with a static contact, and the main conductive base is mounted at the other end; the conductive arm and the pneumatic mechanism are mounted on the main conductive base; the conductive arm is driven by the pneumatic mechanism, and the pneumatic mechanism comprises a speed reducer, a transmission connecting lever and an airpressure control system; the air pressure control system is connected with an input shaft of the speed reducer, an output shaft of the speed reducer is connected with one end of the transmission connecting lever, and the other end of the transmission connecting lever drives the conductive arm to move. The isolating switch is small in occupied space, low in cost, stable and flexible in operation,safe, reliable and convenient to maintain.