Recombinant Anti-HER2 x Anti-HER3 Bispecific Antibody (scFv-CH3) contains two chains. The anti-HER2 scFv is fused to the Knob-CH3 domain via a hinge region and the same as the anti-HER3 scFv to the Hole-CH3 domain, or vice versa. The KIH CH3 domains can facilitate to form a heterodimer and this bivalent binding leads to improvement in avidity. 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.