A backlight module and a flat panel display using the same. The backlight module comprises a light source device and light guide plate adjacent to the light source device. The light source device comprises a high intensity discharge lamp, a reflector having an opening and surrounding the high intensity discharge lamp, and a cover covering the opening. The high intensity discharge lamp radiates so brilliant that it can be a single light source. When single light source is failed, it is convenient to solely exchange a new one at once. The flat panel display comprises the backlight module and a display panel disposed over the light guide plate. The light source device and the light guide plate are applied to the flat panel display so that the replacement of the light source device for the flat panel display becomes convenient.