A device for installing a screen protector, comprising: a screen protector, sequentially including, from top to bottom, a protective layer, an adhesive film layer and a release layer bonded together, wherein the surface of the protector layer is greater than the adhesive film layer and the release layer, and the surface of the adhesive film layer is no larger than the release layer, so that the protective layer and the release layer fully cover the two sides of the adhesive film layer to protect the adhesive film layer from dusts or other sources of contamination before use, wherein the protective layer, the adhesive film layer, and the release layer have openings (111, 121, 131) and grooves (112, 122, 132) corresponding respectively to apertures reserved for the functional structures of a targeted electronic device to which the screen protector is to be applied, an application apparatus being a frame-like structure comprising an internal hollow region formed as through-hole for containing the screen protector and a frame-shaped top surface and being configured for attaching the adhesive film layer of the screen protector onto a surface of the targeted electronic device, and having a certain thickness that can be easily held by hand for installing the screen protector, wherein the protective layer comprises a peripheral portion extended outwardly beyond the adhesive film layer or the release layer characterised in that the peripheral portion attaches to the frame-shaped top surface, and the application apparatus having a certain thickness smaller than the thickness of the targeted electronic device, so that the application apparatus is movable downward vertically along an outer contour of the targeted electronic device after removing a release layer bonded under the adhesive film layer. a screen protector, sequentially including, from top to bottom, a protective layer, an adhesive film layer and a release layer bonded together, wherein the surface of the protector layer is greater than the adhesive film layer and the release layer, and the surface of the adhesive film layer is no larger than the release layer, so that the protective layer and the release layer fully cover the two sides of the adhesive film layer to protect the adhesive film layer from dusts or other sources of contamination before use, wherein the protective layer, the adhesive film layer, and the release layer have openings (111, 121, 131) and grooves (112, 122, 132) corresponding respectively to apertures reserved for the functional structures of a targeted electronic device to which the screen protector is to be applied, an application apparatus being a frame-like structure comprising an internal hollow region formed as through-hole for containing the screen protector and a frame-shaped top surface and being configured for attaching the adhesive film layer of the screen protector onto a surface of the targeted electronic device, and having a certain thickness that can be easily held by hand for installing the screen protector, wherein the protective layer comprises a peripheral portion extended outwardly beyond the adhesive film layer or the release layer characterised in that the peripheral portion attaches to the frame-shaped top surface, and the application apparatus having a certain thickness smaller than the thickness of the targeted electronic device, so that the application apparatus is movable downward vertically along an outer contour of the targeted electronic device after removing a release layer bonded under the adhesive film layer.