The present invention provides a flat panel display device, which includes a backlight system and a display panel, wherein: the backlight system includes a light source, a light homogenization mechanism, and a back frame; the back frame carries the light source and the light homogenization mechanism, the light homogenization mechanism guiding light from the light source to a light incidence surface of the display panel; the back frame includes at least two primary assembling pieces. The at least two primary assembling pieces are joined to form a main frame structure of the back frame in which the at least two primary assembling pieces are joined with multiple space joining spots. The present invention also provides a stereoscopic display device and a plasma display device. The flat panel display device, the stereoscopic display device, and the plasma display device of the present invention have a simple structure and can reduce the expenditure of the back frame mold, and can also save the material used for back frame so as to lower down the cost, and also ensure the strength of the joining site of the back frame and at the same time spread the stress, thereby further ensuring the overall strength of the back frame meets the desired requirements.