The present invention provides a flat panel display device, which includes a backlight system and a display panel. 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, and the light homogenization mechanism guides light from the light source into the display panel. The back frame includes at least two primary assembling pieces and also includes secondary assembling pieces and a bracing piece for fixing a circuit board. According to practical needs of the main frame structure, different materials are used for different parts at different locations. The back frame is provided with the bracing piece for fixing a circuit board, and the bracing piece includes a bracing body, a first suspension section, a first bearing section, and a first resilient bent section. 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 back frame having a simple structure, overcome the problem that a circuit cannot be easily fixed, reduce the expenditure of a back frame mold, and save the material used for back frame so as to lower down the cost of flat panel display device.