Abstract: Objective To explore the role of oval cells in hepatic injure and to study its mechanism. Methods: Fifty male SD rats were randomly divided into normal control group(20 cases) and model group (30 cases). Hepatic pathologic changes were observed under optical microscope and electron microscope . Vimentin and PCNA were detected by immunohistochemistry, Notch1、 RBP-Jκ、HES1 mRNA were detected by semi-quantitative RT-PCR method. Results: The histological morphology was normal in the control group, the positive cells of vimentin and PCNA were found on occasion,the expression of Notch1、RBP-Jκ、HES1 mRNA was low.In the model group ,the oval cells were discovered in portal duct regions massively. The tonofilaments and desmosome juntion which were the distinctive structure of oval cells were observed by electron microscopy. The positive cells of vimentin and PCNA were increased (P<0.01), the expression of Notch1、RBP-Jκ、HES1 mRNA were increased （P<0.01）. Conclusion: The oval cells play an important role in repair of hepatic injury ,the mechanism might relate to Notch family.