A light-emitting substrate and a manufacturing method thereof are provided. The reactivity of part of the ink layer outside the preset area that is far from the light with the first preset wavelength is improved by a heating process. Thus, the part of the ink layer reacts sufficiently under irradiation of the light with the first preset wavelength at lower energy. This improves an undercut issue caused by insufficient curing of the ink layer outside the preset area far from the light with the first preset wavelength, thereby preventing the ink layer from being peeled off from the light-emitting substrate.

The display device includes light emitting elements disposed on a first surface of a substrate, a connection electrode disposed on a second surface of the substrate, a first protective layer disposed on the connection electrode, and a second protective layer disposed on the first protective layer. A surface roughness of the second protective layer is greater than a surface roughness of the first protective layer.