The present application provides a method for manufacturing a fin field-effect transistor, comprising steps of: forming a plurality of strip fins and dummy gates on a substrate, wherein side walls are formed on both sides of the dummy gate; forming a source or a drain on the plurality of strip fins; depositing an interlayer dielectric layer, and performing chemical mechanical planarization (CMP) on the interlayer dielectric layer to expose the top surfaces of the dummy gates; forming a single diffusion break in a single diffusion region; and replacing the dummy gates other than the dummy gate in the single diffusion region with metal gates.