An active region array formation method is provided, including: providing a substrate, and forming a first hard mask layer on a surface of the substrate; patterning the first hard mask layer by using a composite etching process to form an active region shielding layer in the first hard mask layer, a pattern of the active region shielding layer being matched with a pattern of a to-be-formed active region array, wherein the composite etching process includes at least two patterning processes and at least one pattern transfer process; removing the remaining first hard mask layer; and forming the active region array in the substrate through the active region shielding layer.