The invention discloses a large-format high-brightness LED light guide plate ultra-thin light box. The large-format high-brightness LED light guide plate ultra-thin light box comprises a diverging plate, a light guiding-in plate and LED light sources. The diverging plate is engraved with diverging points. One side edge of the light guiding-in plate is a bevel edge, the light guiding-in plate is closely attached to the back face of the diverging plate, and the bevel edge of the light guiding-in plate faces outwards. The LED light sources are arranged on the side, opposite to the bevel edge, of the light guiding-in plate, and light is guided in from the side and is totally reflected by the bevel edge and then enters the diverging plate. Light shading layers are arranged between the side, relatively close to the LED light sources, of the light guiding-in plate and the diverging plate, and the situation that the light of the LED light sources is refracted and then enters the diverging plate is prevented. According to the large-format high-brightness LED light guide plate ultra-thin light box, the large-format high-brightness LED area light sources can be obtained and are especially suitable for an ultrathin LED light guiding-in plate light box. Compared with a side-in type LED light guiding-in plate light box, the large-format high-brightness LED light guide plate ultra-thin light box has the beneficial effect that the brightness is obviously improved. Compared with an area light source with the back face provided with a large number of LED light sources, the large-format high-brightness LED light guide plate ultra-thin light box has the beneficial effects that the uniformity is higher and the thickness is smaller.