Abstract: Based on over 180 HBeAg negative patients' anti-HBV infection therapy data of adefovir dipivoxil with placebo for an international co-operation research and the HBV infection dynamic model proposed by Nowak et al, a mathematical model consisting of two differential equation systems was built. This model provided a possible interpretation of the curative effect of adefovir dipivoxil with placebo for HbeAg negative chronic HBV infection patients, particularly explaining why the plasma virus of the patients turnover after stopping the adefovir dipivoxil therapy. This model predicts the long time adefovir dipivoxil curative effect that the patients whose plasma HBV DNAs is near the median values need to prolong treatment time until 5.6 years to delete HBV virus in bodies. This research implies also that the popular treatment standard of HBV DNA<500 copies·mL^-1 is too rough to evaluate the effectiveness for aniti-HBV infection therapy.