The invention relates to an array substrate manufacturing method, an array substrate and a display device, and belongs to the field of display equipment. The array substrate manufacturing method comprises the following steps of forming a metal pattern with the thickness of (d) on a substrate; forming an insulating film layer on the substrate with the metal pattern; and forming a semiconductor layer and a source and drain metal layer pattern on the substrate with the insulating film layer. The insulating film layer and the metal pattern are overlapped partially, and an absolute value of a height difference between an overlapped region of the insulating film layer and the other region of the insulating film layer is smaller than d. Because the absolute value of the height difference between the overlapped region of the insulating film layer and the other region of the insulating film layer is smaller than d, fluctuation of other patterns formed on the substrate with the insulating film layer is reduced correspondingly, the breakage rate of wires formed on the insulating film layer can be reduced, and the yield of products and be improved.