The utility model relates to a structurally improved illuminant sign plate. On a hollow and sealed sign plate composed of a base and a transparent upper cover, a fixing device is arranged at the rear edge surface of the base, and a convex post arranged on the front edge surface of the base is convexly extended towards the sealed and hollow inner part. The surface of the upper cover is convexly provided with a glyph slot, and the hollow inner part of the sign plate is provided with an illuminant liquid tube and a water-absorbing fabric. The shape of water-absorbing fabrics is the same as that of the glyph slot. When the transparent cover and the base are sealed, different shapes of the sign plate can be made according to needs. When the utility model is used, the illuminant liquid can leaks out by pressing the inner part tube and then be absorbed by the water-absorbing fabric. Therefore, the glyph patterns can be displayed on the surface of the sign plate, and the effect of stable and clear illuminant display can be achieved.