A method for preparing nanowires is disclosed, which comprises the following steps: (a) providing a first precursor solution containing IIB group elements, and a second precursor solution containing VIA group elements; (b) mixing and heating the first precursor solution and the second precursor solution to form a mixed solution; and (c) cooling the mixed solution and filtering the mixed solution to obtain nanowires. The first precursor solution includes compounds of IIB group elements and a surfactant. The second precursor solution includes compounds of VIA group elements. Besides, the surfactant is an organic acid having an aromatic group or a salt thereof.