Disclosed are a display substrate, a fabrication method for the display substrate, and a display device. By arranging a flat layer with a flat surface facing the second metal layer between a first metal layer and a second metal layer, the second metal layer deposited on the flat layer is also relatively flat, so that the second metal wirings with the same width and spacing as that of first metal wirings can be formed. The etching resolutions of the metal wirings in the fanout region corresponding to the first metal layer and the second metal layer in the solutions of the present disclosure can be the same.