A light regulation device includes a first light guide structure having an incident light, a second light guide structure having a light emitting surface, and a light deflection sheet having a first light deflection layer. All or a portion of the incident light is guided by the first light guide structure toward the light deflection sheet, is then deflected at least by the first light deflection layer to travel to the second light guide structure so as to be guided by the same to emit through the light emitting surface. The other portion of the incident light is guided by the first light guide structure toward the second light guide structure, and is then guided by the second light guide structure to emit through the light emitting surface.