A flat panel display device comprising a backboard and a display panel fitted therewith is provided. The edge of the backboard is structured as a barrier wall extending perpendicular to the body of the backboard. A stepped groove is arranged on the interior face of the barrier wall for supporting the display panel and forming accommodating space between the display panel and the body of the backboard. The stepped groove extends from an outer end of the barrier wall towards the body of the backboard, and the depth of the stepped groove is consistent with the thickness of the display panel. The backboard is made of plastic plate containing a enhancing element. The flat panel display device according to the present disclosure can be designed as a light and thin display device with no frame, and thus is suitable for making an all-in-one machine.