The present invention provides a flat panel display device, which includes a backlight system and a display panel, wherein the backlight system includes an LED light source, which includes an LED lamp and an LED substrate carrying the LED lamp; a back frame, which is disposed below the LED substrate and includes at least two primary assembling pieces, the at least two primary assembling pieces being joined to form a main frame structure of the back frame; and a PCB, which is disposed below the back frame and fixed to the LED substrate. The present invention also provides a stereoscopic display device. The flat panel display device and the stereoscopic display device of the present invention save the material and space of the back frame, and lower down the cost of the flat panel display device and the stereoscopic display device.