Provided is a recombinant human G-CSF (rhG-CSF) dimer having prolonged serum half-life and increased biological activity of G-CSF, wherein the dimer is produced by two G-CSF-Fc complexes through the pairing of two Fc fragments via disulfide bonds, and the G-CSF-Fc complex comprises a G-CSF monomer, an Fc fragment of human IgG2, and a peptide connecting the G-CSF monomer and the Fc fragment. The rhG-CSF can be used for the treatment of neurological diseases.