A method for forming a pattern can include the following operations. A substrate is provided, on the surface of which a patterned photoresist layer is formed. Based on the photoresist layer, isolation sidewalls are formed, in which each isolation sidewall includes a first sidewall close to the photoresist layer and a second sidewall away from the photoresist layer. Core material layers are formed between two adjacent isolation sidewalls. The second sidewalls are removed to form the pattern composed of the first sidewalls and the core material layers.