Provided is a method for preparing an array substrate, the array substrate comprising a base substrate (1), wherein a gate electrode (2), a gate insulating layer (3) and a semiconductor layer (4) are sequentially fabricated on the base substrate (1); a second metal layer (12) is then deposited on the gate insulating layer (3) and the semiconductor layer (4), and same is coated with a photoresist layer (10); a photomask process is then used to form source and drain electrodes (5, 6); part of a photoresist region (102') of the photoresist layer (10) is retained on the source and drain electrodes (5, 6) and, once a protective layer (7) is applied, the part of the photoresist region (102') retained on the source and drain electrodes (5, 6) is stripped by a photoresist stripping process, so as to remove the protective layer (7) from the part of the photoresist region (102') on the source and drain electrodes (5, 6) and form a via hole (11); and a pixel electrode (8) is then formed on the protective layer (7) and realizes electrical communication with the source and drain electrodes (5, 6) through the via hole (11), thereby saving the use of one photomask in the manufacturing of the via hole of the protective layer (7). The purpose of saving on the manufacturing cost is achieved by reducing the number of process procedures, including exposure and development, of the traditional process for preparing an array substrate.