Embodiments of the invention disclose an array substrate and a manufacturing method thereof and a liquid crystal display. In the array substrate, an additional electrode is formed above a gate line, the additional electrode and the gate line are spaced from each other by a gate insulation layer, and the additional electrode is connected electrically with the common electrode line; pixel electrode extends to over the additional electrode and is overlapped with the additional electrode, the overlapped portion of the pixel electrode and both the additional electrode and the common electrode line forms a storage capacitor. The liquid crystal display according to the embodiment of the invention comprises the above array substrate.