Four kinds of hepatitis B virus（HBV）DNA vaccines were constructed, two of which encode HBV envelope and core fusion gene，and the others encode HBV envelope or core gene. These DNA vaccines were intramuscularly vaccinated into BALB/c mice respectively. The serum antibodies, T lymphocyte proliferative response and cytotoxic T lymphocyte response of mice were detected. The results showed that the fusion gene DNA vaccines induced weaker antibody, but stronger and longer cellular immune responses than single gene DNA vaccines did, which indicated that the envelope and core fusion gene DNA vaccine may be more useful than single gene DNA vaccine for therapy of hepatitis B.