A patterning method is provided. First, a mask layer and a plurality of first transfer patterns are sequentially formed on a target layer. Thereafter, a plurality of second patterns is formed in the gaps between the first transfer patterns. Afterwards, a plurality of third transfer patterns is formed, wherein each of the third transfer patterns is in a gap between a first transfer pattern and a second transfer pattern adjacent to the first transfer pattern. A portion of the mask layer is then removed, using the first transfer patterns, the second transfer patterns and third transfer patterns as a mask, so as to form a patterned mask layer. Further, a portion of the target layer is removed using the patterned mask layer as a mask.