A stereoscopic display device includes a display panel, a quarter-wave plate and a glass substrate. The display panel includes left-eye pixel line units, right-eye pixel line units and a color filter which including filter units and a black matrix between any two of adjacent filter units. The quarter-wave plate includes first retarders and second retarders. The glass substrate comprises opaque areas, and each opaque area is disposed on the two adjacent first retarder and the second retarder and used for blocking the light from the right-eye pixel line units into the second retarder or the light from the left-eye pixel line units into the first retarder. Therefore, the light corresponding to the right-eye or the left-eye signals is not obscured by the opaque areas even though users watch at a large angle so that it improves crosstalk to optimize 3D image quality.