The invention provides a protection device and a preparation method and application thereof, and relates to the field of protection devices. The preparation method comprises the following steps of drawing a basic protection model according to the size of an object to-be-protected obtained through three-dimensional scanning; digging out the interior of the basic protection model based on a digitalmodel of a to-be-protected object established by three-dimensional scanning to obtain a solid protection model with an inner cavity completely matched with the shape of the to-be-protected object; andcarrying out porous design on a preset area of the solid protection model to obtain a porous protection model; carrying out 3D printing manufacturing on the porous protection model. According to themethod, the inner cavity of the protection device is completely attached to the outer surface of the object to-be-protected, and bumping collision in the transportation process of the object to-be-protected can be effectively avoided; and the protection device can be widely applied to protection devices of various types of cultural relics to achieve the protection of the cultural relics.