A grating element, which is applied in a liquid crystal display device, a) the grating element comprising a plurality of grating element groups (Fig. 3: 1,2,3,4,5; Fig. 4: 1,2,3,4,5,6; Fig. 5: 1,2,3,4,5,6,7,8) for forming dark fringes and transparent fringes, each grating element group comprising dark fringes and transparent fringes, the dark fringe of each grating element group being arranged adjacent to a transparent fringe of a neighboring grating element group, wherein b) each grating element group comprises a plurality of first grating elements (Fig. 3: 1,2,3,4; Fig. 4: 1,2,3,4,5; Fig. 5: 1,2,3,4,5,6,7) and at least one second grating element (Fig. 3: 5; Fig. 4: 6; Fig. 5: 8) arranged parallel to each other, c) at least one of the first grating elements is transparent so as to form the transparent fringe of the grating element group, and different first grating elements are enabled to be transparent so as to change positions of the transparent fringes, d) the second grating element is opaque, and the first grating elements and the second grating element that are opaque are used to form the dark fringes of the grating element group, e) the second grating element has a width greater than that of each of the first grating elements, f) both the transparent fringes and the dark fringes are formed upon orientation of liquid crystal molecules disposed in a liquid crystal layer of the liquid crystal device under the effect of the electric fields created between opposing electrodes (30, 40) of the liquid crystal display device, g) wherein, when there are M first grating elements, each of the first grating elements has a width equal to one N th of the total width of the transparent fringes of the grating element group, where N is an integer less than M and greater than or equal to 2, h) wherein all the first grating elements have an identical width. a) the grating element comprising a plurality of grating element groups (Fig. 3: 1,2,3,4,5; Fig. 4: 1,2,3,4,5,6; Fig. 5: 1,2,3,4,5,6,7,8) for forming dark fringes and transparent fringes, each grating element group comprising dark fringes and transparent fringes, the dark fringe of each grating element group being arranged adjacent to a transparent fringe of a neighboring grating element group, wherein b) each grating element group comprises a plurality of first grating elements (Fig. 3: 1,2,3,4; Fig. 4: 1,2,3,4,5; Fig. 5: 1,2,3,4,5,6,7) and at least one second grating element (Fig. 3: 5; Fig. 4: 6; Fig. 5: 8) arranged parallel to each other, c) at least one of the first grating elements is transparent so as to form the transparent fringe of the grating element group, and different first grating elements are enabled to be transparent so as to change positions of the transparent fringes, d) the second grating element is opaque, and the first grating elements and the second grating element that are opaque are used to form the dark fringes of the grating element group, e) the second grating element has a width greater than that of each of the first grating elements, f) both the transparent fringes and the dark fringes are formed upon orientation of liquid crystal molecules disposed in a liquid crystal layer of the liquid crystal device under the effect of the electric fields created between opposing electrodes (30, 40) of the liquid crystal display device, g) wherein, when there are M first grating elements, each of the first grating elements has a width equal to one N th of the total width of the transparent fringes of the grating element group, where N is an integer less than M and greater than or equal to 2, h) wherein all the first grating elements have an identical width.