A backlit keyboard includes a keyboard module having a plurality of key units and a light guide module including a light guide plate, a metal layer, and an insulation layer. The light guide plate has a light-exit surface and a bottom surface. The metal layer has an upper surface and a lower surface, wherein the upper surface is attached to the bottom surface of the light guide plate. When light is incident onto the upper surface of the metal layer, the light will be reflected back into the light guide plate. When electromagnetic wave reaches the lower surface of the metal layer, the metal layer will shield the electromagnetic wave from propagating. The insulation layer substantially covers the lower surface of the metal layer, wherein at least one ground window is formed in the insulation layer to expose the metal layer.