Objective To study the oxidative damage on testis of male rats induced by micro-nano-scale SiO2. Methods Male Wistar rats were exposed to nanometer SiO2(20-40 nm) and micro-meter SiO2(1-10 ?m)by intratracheal injection once two days. The rats were killed after 5 weeks of exposure. Some indicators related to the oxidative damage in the serum and the testis were determined. Results The activity of GSH-Px and SOD in the high dose groups decreased significantly and the MDA levels increased compared to the control group;The MDA levels of nano-silicon dioxide high dose group increased in the serum. Conclusion Nano-silicon dioxide may cause lipid peroxidation in the testis with a tendency of higher toxicity than that of micro-SiO2 at the same exposed level,the detail mechanism needs further discussion.