Objective To observe the influence to HBV in peripheral blood of Lamivudine combined with plasma exchange. Methods Eleven cases with chronic severe hepatitis B were enrolled and receiced Lamivudine or Lamivudine combined with plasma exchange treatment for 12 weeks. Results There was significant difference of mean antiviral efficacy between the two groups. Conclusion Combinaed therapy of PE and LAM has higher efficacy than LAM alone for inhibiting HBV replication.