The invention is directed to a method for patterning a material layer. The method comprises steps of providing a material layer. The material layer has a first hard mask layer and a second hard mask layer successively formed thereon. Then, the second hard mask layer is patterned to form a plurality of openings therein. A patterned photoresist layer is formed to cover the second hard mask layer and the patterned photoresist layer exposes a portion of the openings. The first hard mask layer with the patterned photoresist layer and the patterned second hard mask layer together as a mask. Then, the patterned photoresist layer and the patterned second hard mask layer are removed. The material layer is patterned with the patterned first hard mask layer as a mask.