Abstract: OBJECTIVE To explore the therapeutic effect and mechanism of quercetin on selenite(Se)-induced cataract model in rats. METHODS SD rats aged 11 d were randomly divided into control group, model group, low-dose quercetin group and high-dose quercetin group with 10 rats in each group. On the 15th day after modeling, cataract formation in each group was examined. The lens was separated and the pathological manifestations of lens were observed by HE staining. The contents of soluble and insoluble protein, malondialdehyde(MDA), and the activities of superoxide dismutase(SOD), glutathione peroxidase(GSH-Px) and glutathione reductase(GSH-Rd) in lens were determined by kits' methods. The expression levels of nuclear nuclear factor E2-related factor 2(Nrf-2) and cytoplasmic heme oxygenase 1(HO-1) in lens were detected by Western blotting. RESULTS Compared with control group, the morphology of lens in model group was significantly changed, and the score of lens opacification, contents of insoluble protein and MDA were significantly increased(P<0.01), while the contents of soluble protein, activities of SOD, GSH-Px and GSH-Rd were significantly decreased(P<0.01); compared with model group, the above conditions in quercetin groups were significantly improved(P<0.05 or P<0.01), especially in the high-dose group(P<0.01). Immunofluorescence results showed that compared with the control group, the protein expression levels of Nrf-2 and HO-1 in the lens of model group were significantly increased(P<0.01) and the protein expression levels of Nrf-2 and HO-1 were further increased after treated with quercetin. Western blotting showed that compared with the model group, the nuclear translocation of Nrf-2 and the protein levels of total Nrf-2 and HO-1 were significantly increased in the quercetin groups(P<0.01). CONCLUSION Quercetin can inhibit the formation of cataract and oxidative stress response induced by Se in rats, and these effects may be related to the enhancement of Nrf-2/HO-1 signal activity.