Recombinant Anti-HER2 x Anti-HER3 Bispecific Antibody (Fab-Fv) is designed to be expressed as two polypeptide chains. The heavy chain Fd fragment and light chain of an anti-HER2 antibody are fused with the VL and VH domains of an anti-HER3 antibody respectively. It can form natural in vivo heterodimerization. This BsAb can bind and inactivate two receptors simultaneously. It is designed for the research of Breast cancer; Gastric cancer; Prostate cacncer; Ovarian cancer; Solid tumors therapy.