Recombinant Anti-pre S2 protein x Anti-S protein Bispecific Antibody (Fab-Fv) is designed to be expressed as two polypeptide chains. The heavy chain Fd fragment and light chain of an anti-pre S2 protein antibody are fused with the VL and VH domains of an anti-S protein antibody respectively. It can form natural in vivo heterodimerization. This BsAb can bind two antigens simultaneously. It is designed for the research of HBV infection therapy.