Objective To evaluate the effect of epigallocatechin gallate on radiation-induced lung injury in rats and to discuss the related mechanism. Methods Rat models of radiation-induced lung injury were produced by 6 MV X ray radiation, and then the animals were divided into model control group and low-, medium- and high-dose (200, 100, 50 mg/\[kg·d\]) epigallocatechin gallate groups. The pulmonary histopathological changes and collagen disposition were observed by H-E staining and Van Gieson (VG) staining, and the scores of alveolitis and pulmonary fibrosis were calculated. The expression of tumor necrosis factor-α (TNFα) and transforming growth factor β (TGFβ) in lung tissues was examined by immunohistochemical (IHC) staining. The activity of superoxide dismutase (SOD) was examined by xanthine oxidase method. Results Apparent alveolitis and pulmonary fibrosis were observed in model rats at 40 d after radiation, and the scores of the alveolitis and pulmonary fibrosis were signficantly lower in medium- and high-dose epigallocatechin gallate groups than in the model control group (P<0.01), and there was no difference between the low-dose epigallocatechin gallate group and the model control group. Pulmonary TNFα and TGFβ expression was significantly lower in the medium- and high-dose epigallocatechin gallate groups than in the model control group and low-dose epigallocatechin gallate groups at 10 d, 20 d, and 40 d after radiation (P<0.01 or P<0.05) , while SOD activity in the former two groups were significantly higher compared with those in the model control group and low-dose epigallocatechin gallate groups(P<0.05). Conclusion Medium- and high-dose epigallocatechin gallate can ameliorate the alveolitis and pulmonary fibrosis in radiation-induced lung injury in rats, which might be associated with the inhibition of TNF-α, TGF-β expression and promotion of SOD activity.