An array substrate and a manufacturing method thereof and a display device are provided, wherein the array substrate includes: a substrate, and a gate electrode, a gate insulating layer, an active layer, a source electrode, a drain electrode and an insulating protection layer sequentially formed on the substrate, and the substrate is further provided with a pixel electrode and a common electrode, and a first leading wire hole connecting the pixel electrode with the drain electrode and a second leading wire hole connecting the common electrode with a common electrode line, the pixel electrode is provided on the substrate, and the gate electrode is directly provided on a transparent conductive layer which is provided at the same layer with the pixel electrode; the pixel electrode is connected with the drain electrode through a first metal connection layer provided in the first leading wire hole, and the first metal connection layer is provided at the same layer with the gate electrode.