Efficacy and Safety of TAF for 48 Weeks in HBeAg Positive CHB Patients

common criteria: * Age 18-70 years old (including both ends), male or female, chronic HBV infection (HBsAg positive for more than 6 months, or liver biopsy results show chronic hepatitis B infection) * HBsAg positive * Patient must be capable of understanding and signing written informed consent; Before commencing the study procedure, participants must obtain informed consent. * Lifestyle requirements: All subjects considered by the investigator to be sexually active and capable of becoming pregnant or making sexual partner become pregnant must agree to use an effective contraceptive method for the entire study period (from the signing of the informed consent to at least 28 days after the last dose of the investigational drug was administered). Addition criteria: Treatment naive patients * HBV DNA\> 2×104 IU/ml * ALT\>2×ULN；or ALT\>1×ULN，but liver biopsy showed inflammation greater than or equal to G2, or/and liver fibrosis greater than or equal to S2 * No treatment with NA or/or αIFN within 1 year ETV treatment experienced patients * ETV treatment for 1 to 2 years before * HBsAg\>3000IU/mL * HBV DNA\<20IU/mL * ALT\<1×ULN * No other NA therapy prior to entecavir treatment * Patients had a desire to convert to TAF therapy Exclusion Criteria: Treatment naive patients * treated with NA or/or αIFN within 1 year * Pregnant women, lactating women, or women who plan to become pregnant within 2 years * Co-infection with Hepatitis C, Hepatitis D or HIV; * Chronic liver disea…