Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (scFv-Fc) is formed by fusing two different scFv fragments to the hinge and Fc regions, in which the Fc region are engineered by KIH. Two of scFv moiety has the antibody variable domain of either anti-CEA specificity or anti-DTPA specificity, which produces bivalent IgG-like molecules with desired characteristics of intact antibodies. This BsAb can be used in pretargeting system of PET, radioimaging or radiotherapy. It can mediate targeting of radioactivity to tumor cells. It is designed for the research of Breast cancer; Ovary cancer; Colon cancer; Lung cancer imaging and therapy.