A slit grating, comprising an upper substrate and a lower substrate arranged hermetically and oppositely to each other to form a cell, and a liquid composite layer arranged between the upper substrate and the lower substrate, wherein the liquid composite layer consists of a light-shielding liquid and a light-transmitting liquid incompatible with each other, a first transparent conductive layer, an insulating layer, a second transparent conductive layer and an electric-controlled dielectric layer are formed sequentially at an upper surface of the lower substrate, and the electric-controlled dielectric layer has an electrically-induced light-shielding-liquid-philic or light-shielding-liquid-phobic property, and the second transparent conductive layer comprises a plurality of parallel, bar-like electrodes, the electric-controlled dielectric layer comprises a plurality of bar-like electric-controlled dielectric sublayers corresponding to regions where the bar-like electrodes are located, and the bar-like electrodes and the first transparent conductive layer are configured to control each bar-like electric-controlled dielectric sublayer separately to absorb or repel the light-shielding liquid, thereby to facilitate an adjustment of slit positions of the slit grating; when there are N viewpoints for a 3D display, an electric potential of a bar-like electrode is negative every other N-1 bar-like electrodes, such that the corresponding bar-like electric-controlled dielectric sublayers are configured to repel the light-shielding liquid, to enable the light-transmitting liquid to take a place of the light-shielding liquid to form light-transmitting stripes; and an electric potential of the remaining bar-like electrodes is positive, such that the corresponding bar-like electric-controlled dielectric sublayers are configured to absorb the light-shielding liquid to form light-shielding stripes; each bar-like electric-controlled dielectric sublayer consists of a plurality of electric-controlled dielectric blocks separated from each other; a plurality of crisscross partitioning walls are formed at the upper surface of the lower substrate so as to divide the upper surface of the lower substrate into a plurality of hermetical regions in a matrix form, and the liquid composite layer is filled within each hermetical region, the hermetical region extends horizontally over a second plurality of N bar-like electrodes; wherein the plurality of parallel, bar-like electrodes all have an equal width and an equal spacing. wherein the liquid composite layer consists of a light-shielding liquid and a light-transmitting liquid incompatible with each other, a first transparent conductive layer, an insulating layer, a second transparent conductive layer and an electric-controlled dielectric layer are formed sequentially at an upper surface of the lower substrate, and the electric-controlled dielectric layer has an electrically-induced light-shielding-liquid-philic or light-shielding-liquid-phobic property, and the second transparent conductive layer comprises a plurality of parallel, bar-like electrodes, the electric-controlled dielectric layer comprises a plurality of bar-like electric-controlled dielectric sublayers corresponding to regions where the bar-like electrodes are located, and the bar-like electrodes and the first transparent conductive layer are configured to control each bar-like electric-controlled dielectric sublayer separately to absorb or repel the light-shielding liquid, thereby to facilitate an adjustment of slit positions of the slit grating; when there are N viewpoints for a 3D display, an electric potential of a bar-like electrode is negative every other N-1 bar-like electrodes, such that the corresponding bar-like electric-controlled dielectric sublayers are configured to repel the light-shielding liquid, to enable the light-transmitting liquid to take a place of the light-shielding liquid to form light-transmitting stripes; and an electric potential of the remaining bar-like electrodes is positive, such that the corresponding bar-like electric-controlled dielectric sublayers are configured to absorb the light-shielding liquid to form light-shielding stripes; each bar-like electric-controlled dielectric sublayer consists of a plurality of electric-controlled dielectric blocks separated from each other; a plurality of crisscross partitioning walls are formed at the upper surface of the lower substrate so as to divide the upper surface of the lower substrate into a plurality of hermetical regions in a matrix form, and the liquid composite layer is filled within each hermetical region, the hermetical region extends horizontally over a second plurality of N bar-like electrodes; wherein the plurality of parallel, bar-like electrodes all have an equal width and an equal spacing.