Abstract: Objective To research the level of protein oxidation damage induced by SO₂ inhalation and the mechanism of its toxicological effect on prote in in brain and stomach tissues in mice.Methods After exposure to SO₂ inhalation at 3 different concentrations(14, 28, and 56 mg/m³), the levels of prote in carbonyl(PCO) and DNA protein crosslinks(DPC) were analyzed with spectrophotome tric 2.4-d initrophenylhydrazine (DNPH) assay and potassium chlorine-sodium dodecyl sulfate(KCl-SDS) assay.Results SO₂ could cause the formation of PCO and DPC in brain of mice in a dose-effect relation ship(r² 0.984 0).The contents of PCO in the brain increased by 17.4%, 38.2%, and 72.9% when the concentration of SO₂ were 14, 28, and 56 mg/m³, respectively, while the contents of DPC increased by 15.2%, 22.1%, and 42.8%.But only when the concentrations of SO₂ were 28 and 56 mg/m³, the PCO and DPC contents were significantly higher than those of the control group(P<0.05).The inerease of DPC in the female mice was higher than that of in the male mice.But the increases of PCO and DPC in stomach after SO₂ inhalation were not statistically significant.Conclusion SO₂ inhalation could significantly increase the levels of PCO and DPC in brain, but not in stomach in mice.