Abstract: Objective To investigate the role of hepatitis B virus X（HBX） protein in cell apoptosis. Methods Eukaryotic expression vector of HBX gene was constructed. Recombination vector mentioned above was transfected by Lipofectamine to Hela cell, Hepatocarcinoma cell（SMMC- 7721） and normal mouse fetal liver cell（FL）. X protein（pX） expressed in these three cell type was detected by immunohistochemical method. The apoptosis in Hela- X cells was analyzed by flow cytometry and the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate fluorescence nick end labeling（TUNEL）method. Results In three cell type, pX expressed. A stable pX- expression cell line was selected by G418. HBX protein could express in Hela cells in 20 passages. Conclusion HBX protein could induce apoptosis in vitro.