Disclosed is the use of a fusion protein in drugs for stimulating differentiation of bone marrow mesenchymal stem cells to hematopoietic stem/progenitor cells, or drugs for proliferation of granulocyte hematopoietic progenitor cells. The fusion protein has a sequence as shown in SEQ ID NO: 2 or SEQ ID NO: 4. The drugs can be used for the prevention and/or treatment of (i) hematopoietic dysfunction caused by chemotherapy, (ii) hematopoietic dysfunction caused by radiotherapy, or (iii) leukopenia.
