A method for manufacturing an array substrate, an array substrate and a display panel are provided. The method includes forming patterns of a gate metal layer and a gate insulating layer successively on a base plate, forming a pattern of a semiconductor layer, where the pattern of the semiconductor layer comprises a pattern of an active region and a pattern of a pixel electrode region, the semiconductor layer comprises an insulative oxide layer and a semiconductive oxide layer stacked on the insulative oxide layer, and the insulative oxide layer is located between the gate insulating layer and the semiconductive oxide layer, forming a pattern of a source and drain metal layer, and subjecting the semiconductive oxide layer in the pixel electrode region to plasma treatment, to convert the semiconductive oxide layer in the pixel electrode region into a conductor.