Abstract: Objective To investigate the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) mobilization therapy on lymphocyte subsets and immune function in peripheral blood of the normal stem cell donors. Methods Hematopoietic stem cell mobilization and collection were performed on 57 normal stem cell donors in the Department of Hematology, General Hospital of Guangzhou Military Command from January 2017 to March 2018. RhG-CSF (5-10 μg·kg^-1·d^-1) was administered subcutaneously for 5 days to mobilize hematopoietic stem cells (HSCs). Peripheral blood from donors was collected on the 0th, 3rd, and 5th day after the mobilization therapy. Then lymphocyte subsets were detected by using flow cytometry. Immunoglobulins and complements were detected by using automatic biochemical analyzer. Results In the peripheral blood of donors on day 0, 3, and 5 after mobilization therapy, the percentage of total lymphocytes decreased, and the decrease was particularly significant on the 5th day of mobilization (P<0.05). The proportion of total T cells (CD3⁺), T helper cells (CD3⁺CD4⁺), and B lymphocytes (CD19⁺) increased on the 3rd day of mobilization and decreased on the 5th day, but the difference was not statistically significant (P>0.05). The subpopulations of cytotoxic T lymphocytes (CD3⁺CD8⁺) and NK cells (CD3^-CD56⁺) showed a downward trend after mobilization, but the difference was not statistically significant (P>0.05). The CD4⁺/CD8⁺ ratio showed an upward trend, but without statistically significance (P>0.05). There were no significant changes in the levels of immunoglobulins (IgA, IgG, IgM) and complements (C3, C4) in the peripheral blood of the donors on days 0, 3 and 5 of mobilization (P>0.05). Conclusion The rhG-CSF mobilization therapy does not affect lymphocyte subsets and immune function in the peripheral blood of normal stem cell donors, which can be safely applied to hematopoietic stem cell mobilization.