A semiconductor light-emitting device includes a conductive substrate, a light-emitting structure layer, a metallic reflective layer, a transparent conductive layer, a first patterned dielectric layer, and a second patterned dielectric layer. The light-emitting structure layer, the transparent conductive layer, the metallic reflective layer, and the conductive substrate are sequentially arranged. The first patterned dielectric layer is between the light-emitting structure layer and the transparent conductive layer and includes first structure units separated from one another by a first space. The first portions are located in the first spaces respectively. The second patterned dielectric layer is between the transparent conductive layer and the metallic reflective layer and includes second structure units separated from one another by a second space. The second portions are located in the second spaces respectively. The first and the second portions are not overlapped.