Methods for fabricating array substrates are provided. A method for fabricating an array substrate includes forming a first metal layer over a substrate and then patterned by a first photolithography to forming a gate line, a gate electrode connecting the gate line, and a pad over the substrate. An insulating layer, a semiconductor layer, and an ohmic contact layer are formed over the substrate to cover the gate line, the gate electrode and the pad. The ohmic contact layer, the semiconductor layer, and portions of the insulating layer are patterned by a second photolithography to forming a semiconductor structure over the substrate and a via hole in the insulating layer over the pad to exposing a part of the pad.