Recombinant Anti-CA125 x Anti-HER2 Bispecific Antibody (F(ab')2-scFv2) is designed to be expressed as two chains combined via a hinge region. The scFv of the anti-CA125 specificity is fused to the C terminus of the anti-HER2 Fab fragment, or vice versa. This format comprises four binding sites (two same scFv regions and two same Fab fragments), two for each antigen. 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.