A manufacturing method of a semiconductor device comprises the steps of: providing a transparent substrate; forming a gate electrode on the transparent substrate; forming a gate insulation layer covering the gate electrode; forming an oxide semiconductor layer on the gate insulation layer and at least partially over the gate electrode; forming an etching stop layer over the gate electrode and at least covering a part of the oxide semiconductor layer, wherein the etching stop layer includes an opening; forming an electrode layer at the opening and on a part of the etching stop layer; and applying a low-resistance treatment to a part of the oxide semiconductor layer uncovered by the etching stop layer and the electrode layer to form a pixel electrode.