Objective To investigate the radioprotective effect of jackfruit oligopeptides (JOPs). Methods One hundred and forty-four specific pathogen free(SPF)female BALB/c mice were randomly divided into blank control group, model control group, whey protein group (0.40 g/kg BW) and 3 JOPs intervention groups (0.20,0.40,0.80 g/kg BW) with 24 in each group. Each group was randomly divided into 3 subgroups, 8 per subgroup. On the 14th day of the intragastric administration, the mice except the blank control group received ⁶⁰Co γ-ray whole body irradiation, and intragastric intervention continued after irradiation. The first subgroup of each group (8 Gy, 1 Gy/min) was subjected to 30 d survival test, and the other two subgroups (3.5 Gy, 1 Gy/min) were used to detect peripheral blood white blood cells (WBC), bone marrow DNA content, weight changes and organ indexes of liver, spleen and thymus on the 3rd and 14th day after irradiation, respectively. Results Compared with the model control group, the survival time of the medium and high dose group of JOPs was significantly prolonged(P＜0.05). On the 3rd and 14th day after irradiation, the WBC number, the DNA content of bone marrow cells, the liver and spleen indexes in the JOPs intervention groups were significantly increased(P＜0.05). Besides, the thymus index of the low and middle dose groups of JOPs increased significantly on the 14th day after irradiation(P＜0.05). Furthermore, the efficacy of JOPs was superior to those of whey protein. Conclusion JOPs had protective effects against ionizing radiation exposure.