This invention relates to a use of G-CSF dimer in the treatment of neutropenia. In particular, the recombinant human G-CSF of the present invention can enhance the differentiation and development of neutrophils in animal, and thus effectively reduce the severity of the severe neutropenia and shorten the time of severe neutropenia for the post-chemotherapy cancer patients. Serum half-life of G-CSF dimer of this invention is prolonged and the biological activity thereof is increased, providing a better effect in the treatment of neutropenia.
