The invention relates to an epitope peptide (or a variant thereof) which can be used for treating hepatitis B virus (HBV) infection, a recombinant protein containing the epitope peptide (or the variant thereof) and a carrier protein, and applications of the epitope peptide (or the variant thereof) and the recombinant protein. The invention also relates to antibodies of the epitope peptide, cell strains capable of producing the antibodies, and applications of the antibodies and the cell strains. In addition, the invention relates to a vaccine or a pharmaceutical composition which are both capable of treating HBV infection or alleviating one or a plurality of kinds of symptoms relating to HBV infection. The vaccine and the pharmaceutical composition respectively comprise the recombinant protein or the antibodies.