A semiconductor light-emitting device and a manufacturing method thereof are provided, wherein the semiconductor light-emitting device includes a first type doped semiconductor structure, a light-emitting layer, a second type doped semiconductor layer, a first conductive layer and a dielectric layer. The first type doped semiconductor structure includes a base and a plurality of columns extending outward from the base. Each of the columns includes a top surface and a plurality of sidewall surfaces. The light-emitting layer is disposed on the sidewall surfaces and the top surface, wherein the surface area of the light-emitting layer gradually changes from one side adjacent to the columns to a side away from the columns. The dielectric layer exposes the first conductive layer locating on the top surface of each of the columns, wherein the dielectric layer includes at least one of a plurality of quantum dots, phosphors, and metal nanoparticles.