Abstract: Objective To investigate the effects of Rock2 on radiation sensitivity of hepatocellular carcinoma cells (HCC). Methods The expression of Rock2 in HepG2 and Huh-7 cells was decreased and DNA damage model was constructed by IR exposure.MTT assay was used to detect cell proliferation.The change of Cdc25A expression was measured by Western blot and Cdk2/CyclinE activity was detected by fluorescence resonance energy transfer. Results shRock2 cells exposed to IR(to induce DNA damage) showed significantly decreased survival,compared with siControl cells.Western blot analysis revealed that when exposed to IR，Cdc25A decreased more obviously in shRock2 cells as compared to siControl cells.After exposure to IR，the decreased in Cdk2/Cyclin E activity was more apparent in shRock2 cells compared to the siControl cells. Conclusion Inhibition of Rock2 expression could enhance the radiation sensitivity of HCC by suppressing Cdc25A.Rock2 might be a new target gene for treatment of HCC.