Forty-eight mice were randomly divided into eight groups of six mice each. Group 1 was the control group, groups 2, 3, and 4 were the Potentilla anserina L drug groups, group 5 was the irradiation group, and groups 6, 7, and 8 were the irradiated Potentilla anserina L drug groups. The control group was administered distilled water by gavage for 5 d without irradiation; the irradiation groups were irradiated with 5 Gy ⁶⁰Co γ rays. In the drug groups, the mice were gavaged with distilled water and Potentilla anserina L polysaccharide within 30－60 min after irradiation for 5 d and euthanized on the sixth day. The effects of different doses of Potentilla anserina L polysaccharide on the blood routine, organ index, DNA content in bone marrow, superoxide dismutase (SOD) activity, total antioxidant capacity (T-AOC), lymphocyte subpopulation ratio, and malondialdehyde (MDA) content in the mouse livers were determined. The results showed that Potentilla anserina L polysaccharide increased the erythrocyte and leukocyte counts, hemoglobin content, and erythrocyte-specific volume as well as the spleen index, liver T-AOC, SOD activity, and lymphocyte count and decreased the MDA content. The DNA coefficient of irradiated mice was improved to some extent. Potentilla anserina L polysaccharide exert good therapeutic effect on the hematopoietic and antioxidant systems and can mitigate the DNA damage of bone marrow cells in radiation-injured mice.