Objective To explore the establishment of a rat model of acute radiation-induced liver injury and sig-nificance of the dynamic changes of TGF-β1 expression.Methods Forty healthy 6-week old male SD rats were randomly divided into model group (n=30) and control group (n=10).The right liver of rats in the model group was given a single dose of 25 Gy 6 MV X-ray irradiation.Histopathological examination using HE staining and transmission electron microsco-py were conducted to observe the liver pathological changes in rats at 3, 5, and 10 days after irradiation, serum TGF-β1 was detected, and relevant indicators of liver function ( ALT, AST, ALP) were determined.Statistical analysis was per-formed using SPSS 17.0 software.Results At 3, 5 and 10 days after irradiation, early pathological changes in the liver cells were observed by electron microscopy, the expression of TGF-β1 was gradually increased with the time prolongation, and significant differences were found between the model group and the control group at different time points (P<0.05). The light microscopic observation of liver tissues did not show significant differences between the control group and model group.The liver ALT, AST, ALP at different time points did not show significant differences between the two groups ( P>0.05).Conclusion Electron microscopy can be used to evaluate the early changes of radiation-induced liver injury, pri-or to the alterations visible by routine light microscopy.TGF-β1 can be used to predict the degree of radiation-induced liver injury, and may be used as a sensitive serum cytokine in predicting the degree of radiation-induced acute liver injury.