This is a prospective study to evaluate the safety and efficacy of Sintilimab (PD-1 antibody) in sequential combination with Peg-IFNα-2b in NA-supressed CHB patients who had previously received Peg-IFNα therapy.

Inclusion Criteria:

• 1. 18 - 65 years old;
• 2.Chronic hepatitis B patients with clear diagnosis of hematology, etiology and clinical (for example: HBsAg positive for more than 6 months);
• 3. In virologically suppressed (HBV DNA below the lower detection limit) CHB patients by NAs treatment, HBsAg decreased by less than 0.5log in the last 6 months of Peg-IFNα therapy, and then discontinued Peg-IFNα at least 6 months;
• 4.Patients with HBV DNA negative, HBeAg negative, HBsAg quantification ≤ 200IU/ml at Peg-IFNα discontinuation and enrollment.

Exclusion Criteria:

• 1. Cirrhosis;
• 2.platelet count < 90×109/L, WBC count < 3.0×109/L, neutrophil count < 1.3×109/L, ALT > ULN (40U/L), total bilirubin > 2ULN;
• 3.History of or suspicion of hepatocellular carcinoma
• 4.Patients received immunosuppressive therapy or other therapy influenced study within 12 months;
• 5.Hepatitis A, hepatitis C, hepatitis D, HIV infection or other active infections;
• 6.Alcohol or drug abuse/dependence;
• 7.Investigator judges that the participants are not suitable for this study.