Abstract: Objective：To study the inhibitory effect on hepatitis B virus of HBsAg ScFv，HBsAg ScFv gene.Methods：HBsAg ScFv gene was screened and identified from a sem-i synthetic phage library by phage display technique and amplified and cloned into the retroviral vector pLXSN.The reconstructed plasmid pLXSN-HBsAg ScFv was transfected into PA317 cells and infected 2.2.15cells by using the supernatant containing the pseudovirus.Then，HBsAg and HBeAg were detected by ELISA and the density of HBV DNA was tested by quantitative determination.Results：The specific HBsAg ScFv was screened and cloned into retroviral vector pLXSN.HBsAg ScFv pseudovirus contained in the supernatant of transfected PA317 cells were identified by RT-PCR.When the HBsAg ScFv pseudovirus were infected into 2.2.15 cells and incubated for 3，5，7，14days，the P/N value of HBsAg and HBeAg were decreased gradually and turn to negative at day 14.The density of HBV DNA had not changed apparently.Conclusion：The results indicated that HBsAg ScFv gene expressing in 2.2.15cells can inhibit the expression of HBV significantly and it may be a potential candidate for gene therapy against HBV infection.