Recombinant Anti-CEA x Anti-TNFα Bispecific Antibody (Fab-Fv) is designed to be expressed as two polypeptide chains. The heavy chain Fd fragment and light chain of an anti-CEA antibody are fused with the VL and VH domains of an anti-TNFα antibody respectively. It can form natural in vivo heterodimerization. This BsAb can retarget cytokine (TNFα) to tumor cells. It is designed for the research of Breast cancer; Ovary cancer; Colon cancer; Lung cancer therapy.