An auto-stereoscopic display device is proposed. The auto-stereoscopic display device includes a display panel and a liquid crystal lens. The liquid crystal lens includes a first electrode layer and a second electrode layer. The first electrode layer includes a plurality of first electrode stripes arranged in parallel along pixel units and extending in a first or second direction. The second electrode layer includes a plurality of second electrode stripes extending slantingly relative to the plurality of first electrode stripes and being arranged in parallel. A liquid crystal lens and a driving method thereof are also proposed. Based on the present invention, a first lenticular lens unit is generated and arranged along the plurality of second electrode stripes for the 3D display mode, and a second lenticular lens unit is generated and arranged along the plurality of first electrode stripes for the 2D display mode. The invention can fulfill the 3D-mode requirement and enhance brightness and luminance in the 2D mode.