The invention discloses an adjusting device of an intra-cavity ultrasonic probe protection device and an application thereof. The adjusting device is used for prostate biopsy or radioactive particle implanting and comprises a tightening component, a fixing component, a guiding component and a connecting component. The tightening component is arranged on the fixing component, and a fixing portion is arranged on the fixing component and used for installing and fixing an ultrasonic probe protection sleeve. One end of the guiding component is movably connected with the fixing component, and the other end of the guiding component is fixedly connected with the connecting component. The connecting component is arranged below the fixing component and fixedly connected with the guiding component. Under the action of the tightening component, the fixing component can move along the guiding component; when the fixing component gets close to the connecting component, the ultrasonic probe protection device moves downwards and is close to the surface of an ultrasonic probe so that the ultrasonic probe protection device and the ultrasonic probe can be kept attached well; air in the space, between the inner wall of the upper portion of the ultrasonic probe protection sleeve and the external surface of the upper portion of the ultrasonic probe, for filling of medicinal ultrasonic coupling agents, is discharged, imaging quality is improved, and the usage quantity of the coupling agents is reduced.