Objective To evaluate the radioprotective effects of Quercetin (QN) on 6 Gy X-ray irradiation-induced immune dysfunction and toxicity in hepatic tissue in rats. Methods 40 adult rats were randomly divided into 4 groups. Group Ⅰ was injected intraperitoneally with saline solution for 7 consecutive day sand served as control group. Group Ⅱ was daily injected with QN (40 mg/kg) for 7 consecutive days. Group Ⅲ was irradiated with a single dose of 6 Gy X-ray. Group Ⅳ received a daily injection of QN (40 mg/kg) for 7 consecutive days, and 1 h after the last injection rats were irradiated with a single dose (6 Gy) X-ray irradiation.The animals were sacrificed after 24 h. Lymphocyte transforming rate was measured with MTT method, and CD+4 T, CD+4 T and CD+8/CD+8 T were measured with flow cytometry method. Oxidative conditions in liver were measured with malondialdehyde (MDA), reduced glutathione hormone (GSH), supernxide dismutase (SOD) andglutathione peroxidase (GSH-Px) activities kits. HE staining was used to observe the general condition of rat's liver. Results Lymphocyte transforming rate, CD+4 T, CD+8 T and CD+8/CD+8 T in rats of Group Ⅳ were all higher than those in rats of Group Ⅲ ( F = 8.455,22.644, 18.911, P < 0.01 ). MDA content in the Group Ⅳ rat's liver was lower than that in the Group Ⅲ ( F = 10.059, P < 0.01 ) and antioxidant enzymes SOD, GSH-Px activities were higher than those in Group Ⅲ (F = 23.688,186.046,19.788, P < 0.01 ). The capillary of the hepatic lobules dilated and congested obviously in portal area, involving infiltration of polymorphonuclear leukocytes in the Group Ⅲ, while QN improved this change apparendy. Conclusions Pretreatment with Quercetin improved the irradiated rat's immune functions and protected the irradiated rats from oxidative stress to some extent.