Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (Triple Body) is designed to be expressed as two polypeptide chains respectively. The Fd fragment and LC from an anti-CEA antibody are both extended with the scFv fragment from an anti-DTPA antibody. 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.