A manufacturing method of an optoelectronic semiconductor device includes: providing a matrix substrate, which comprises a substrate and a matrix circuit disposed on the substrate; transferring a plurality of micro-sized optoelectronic semiconductor elements from a temporary substrate to the matrix substrate, wherein the micro-sized optoelectronic semiconductor elements are separately disposed on the matrix substrate, and at least one electrode of each micro-sized optoelectronic semiconductor element is electrically connected with the matrix circuit; forming a protective layer completely covering the micro-sized optoelectronic semiconductor elements, wherein the height of the protective layer is greater than the height of the micro-sized optoelectronic semiconductor elements; and grinding the protective layer until a residual on a back surface of each micro-sized optoelectronic semiconductor element and the back surface are removed to expose a new surface.