In the present study, the therapeutic effects of 5-androstenediol on radiation-induced myeloid suppression and tissue damage in mice and the possible mechanism were explored. The mice were subjected to whole-body irradiation, and 5-androstenediol was administered subcutaneously at different times and doses. The evaluation of the survival rate showed that the administration of 5-androstenediol every three days post-irradiation was the most effective in decreasing the death of the mice. Additionally, 5-androstenediol dose-dependently reduced the death caused by 9 Gy radiation. The pharmacological mechanism was investigated by blood analysis, western blot analysis, immunofluorescence and immunohistochemistry. 5-Androstenediol significantly ameliorated myeloid suppression, as demonstrated by elevated levels of total white blood cells, including neutrophils and platelets, in the peripheral blood. By H&E staining, we found that radiation-induced myeloid suppression in the bone marrow and spleen, as well as tissue damage in the lung and colon, was significantly ameliorated by treatment with 5-androstenediol. Immunohistochemistry showed elevated phosphorylation of p65 in the bone marrow and spleen, indicating the activation of NF-κB signaling. Moreover, 5-androstenediol markedly hampered the radiation-induced activation of caspase-1 and GSDMD in the colon by decreasing the interaction between AIM2 and ASC. Taken together, our results suggest that, by promoting NF-κB signaling and inhibiting inflammasome-mediated pyroptosis, 5-androstenediol can be used as a radioprotective drug.