Recombinant Anti-pre S2 protein x Anti-S protein Bispecific Antibody (Fab-scFv-Fc) requires expression of three polypeptide chains, encoding two heavy chains (Fc-containing chains) and one light chain, respectively. The Fab of anti-pre S2 protein antibody variable domain is fused to the Fc-knob domain with a hinge region and the same as the scFv of anti-S protein to the Fc-hole domain, or vice versa. The Fab-Fc and scFv-Fc fragments can be paired via the interaction of the Fc regions. This BsAb can bind two antigens simultaneously. It is designed for the research of HBV infection therapy.