Recombinant Anti-HER2 x Anti-HER3 Bispecific Antibody (IgG-Fv) is formed by an Immunoglobulin G (IgG) and a fragment variable Fv region, in which the Fc of IgG is engineered by KIH. The Fv region of an anti-HER2 antibody variable domain is fused to the C terminal of an IgG of anti-HER3 antibody, or vice versa. The format retains desired characteristics of intact antibodies. 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.