A manufacturing method of a light-emitting device, comprising providing a growth substrate; forming a light-emitting stack on the growth substrate, the light-emitting stack comprising a first surface, a second surface opposite to the first surface, and a sidewall connecting the first surface and the second surface; forming a patterned dielectric layer on the first surface, the patterned dielectric layer comprising a first portion and a second portion separated from the first portion; attaching a permanent substrate to the light-emitting stack; removing the growth substrate after the permanent substrate is attached to the light-emitting stack; forming a plurality of trenches in the light-emitting stack to form a plurality of light-emitting units, wherein the plurality of light-emitting units are insulated from each other; and cutting along the plurality of trenches, wherein an outer part of the second portion of the patterned dielectric layer is thinned.