Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (IgG-Fv) is formed by an Immunoglobulin G (IgG) and a fragment variable Fv region, in which the Fc of IgG is engineered by KIH. The Fv region of an anti-CEA antibody variable domain is fused to the C terminal of an IgG of anti-DTPA antibody, or vice versa. The format retains 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.