Recombinant Anti-CA125 x Anti-HER2 Bispecific Antibody (scFv-CH3) contains two chains. The anti-CA125 scFv is fused to the Knob-CH3 domain via a hinge region and the same as the anti-HER2 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 two factors simultaneously. It is designed for the research of Breast cancer; Gastric cancer; Prostate cacncer; Ovarian cancer; Solid tumors therapy.