Objective To investigate the effects of CeO2NPs sub-acute exposure on body weight, organ structures and redox indicators in male mice. Methods 35 male ICR mice were randomly divided into five groups with seven mice in each group. Normal control group and CeO2NPs (100, 500, 1000, 5000 ug/kg) test groups were set up. Mice were injected CeO2NPs intraperitoneally every other day for 28 days. Results Compared with the control group, there was no significant difference in weight gain (P>0.05) , but there was significant difference in liver coefficient, epididymal coefficient and sperm survival rate (P<0.01). In the 5000 ug/kg group, CeO2NPs were deposited in the liver and spleen, and granuloma was found. The activities of SOD and GSH-Px in serum of 100 ug/kg group were increased, while the content of MDA was decreased, which showed the antioxidant effect of CeO2NPs. With the increase of dose, the oxidative stress induced by CeO2NPs was enhanced. Conclusion The low dose of CeO2NPs is safe and has antioxidant effect. With the increase of dose, the toxicity of CeO2NPs to the body also increases gradually.