A semiconductor fin fabrication method includes: providing a substrate; selectively epitaxially growing a first mask layer in a predetermined zone on the substrate; selectively epitaxially growing a first epitaxial layer on the substrate by using the first mask layer as a mask; and removing the first mask layer and a part, under the first mask layer, of the substrate by using the first epitaxial layer as a mask and by using an anisotropic etching method, so as to form a fin under the first epitaxial layer. According to the foregoing solutions, a manner in which a selective epitaxial growth technology and an anisotropic etching technology are combined is used It can be ensured that a semiconductor fin and a surface of a gate oxidized layer are perpendicular to each other, roughness of a surface of the semiconductor fin is reduced, and a fin with a smooth side surface is formed.