A method for forming micro-patterns is disclosed. The method forms a sacrificial layer and a mask layer. A plurality of first taper trenches is formed in the sacrificial layer. A photoresist layer is filled in the plurality of first taper trenches. The photoresist layer is used as a mask and a plurality of second taper trenches is formed in the sacrificial layer. Then, the photoresist layer is stripped to be capable of patterning a layer by the first taper trenches and the second taper trenches in the sacrificial layer. Therefore, a patterned sacrificial layer duplicating the line density by double etching is formed.