The invention provides a switching device for high-voltage partial discharge models under the high air pressure. The switching device is used for a partial discharge test for a cavity of a gas insulated metal-enclosed switchgear (GIS). The switching device is composed of the partial discharge models, telescopic push rods, a high air-pressure sealed cavity, a cavity high-voltage electrode, and a controller. Each telescopic push rod is controlled by the controller to be pushed out or retracted, so that one partial discharge model is pushed out to contact with the cavity high-voltage electrode, or one partial discharge model is retracted to be away from the cavity high-voltage electrode. The lengths of the partial discharge models and the flexible ranges of the push rods are calculated according to an insulation distance to enable the retracted partial discharge model not to affect the discharge performance of the extended partial discharge model. According to the device, the efficiency and accuracy of the partial discharge test for a GIS device are improved, and the potential personal security risk during the test is reduced.