Adault male mice were irradiated with γ-rays 6 Gy once or 3 Gy three times in 7 days and intraperitoneally injected with colony-stimulating factor(CSF) in high doses or low doses. Mice of the control group were injected with normal saline only. Within 30 days after irradiation, the survival rate of mice irradiated with 6 Gy γ-rays once and treated with high dose CSF was 9/25, while that in the control group was 2/25. The survival rate of mice irradiated with 3 Gy three times and treated with high dose CSF was 10/13, while that in the control group was 4/13. Moreover, the survival times of both irradiated groups treated with high dose CSF were much longer than the control groups (,p,<,0.01). This experiment also showed that CSF could reduce the lowering of peripheral blood white blood cell counts and promote their recovery. The number of CFU-S in mice treated with CSF was much higher (23.8±4.82) than in the control group (9.4± 4.39) (,p,<,0.01). Therefore, CSF could recover and reconstruct the hematopoietic function of bone marrow, and prolong the survival of irradiated mice.