The invention provides a height limiting signboard for 10KV overhead lines. The signboard comprises a base plate, a light absorbing layer which covers the surface of the base plate, a light reflecting part which is arranged on the surface of the light absorbing layer, and a protecting layer which covers the light absorbing layer and the light reflecting part, wherein the light reflecting part comprises an outer light reflecting frame, and a light reflecting block which is surrounded by the outer light reflecting frame and is of a font shape, or a graph shape, or a combined shape of the font and the graph; the protecting layer is a transparent protecting layer; first hooking parts which are used for hooking on the 10KV overhead lines are arranged at the edge of the top of the base plate; the base plate, the light absorbing layer, the light reflecting part, the protecting layer and the hooking parts are respectively insulators. The signboard can play the role of prompt, the caution for supply lines is realized, accidents that guide lines are touched by vehicles, ships and the like are reduced, and line breaking and rod breaking of the overhead lines are reduced.