A method for manufacturing an array substrate is disclosed and includes steps of: sequentially forming a first metal layer, an insulating layer and a second metal layer on a glass substrate; forming a passivation layer on the second metal layer; performing a first etching process on the passivation layer to obtain a first groove and a second groove; performing a second etching process on the passivation layer to obtain a third groove; and forming a pixel electrode layer on the passivation layer. The method saves one photomask and a photolithography step, thereby reducing the cost and improving the efficiency.