The expression vector, pET21-CEA-streptavidin was constructed which contains the gene of single chain antibody of CEA(ScFv) and the streptavidin. Constructed vector was expressed by Escherichia coli. The results showed that such protein was successfully prepared and its bispecific activities were testified by affinity blot and Western blot. The biotin binding and immunocytochemistry assay indicated that the expressed fusion protein was capable of binding biotin molecule and CEA antigen respectively. This protein has the potential application when combined with the corresponding tests.