Artificial antigen Cd-IEDTA-BSA (HSA) was successfully synthesized by the bifunctional chelating agent IEDTA (isothiocyanobenzylethyl enediamine tetraacetic acid) coupling with cadmium and protein carrier. The fluorescence characteristics of antigen were determined by fluorescence spectrophotometry and the coupling ratio 11∶ 1-16∶ 1 was obtained for the coupling reaction. The folding status of serum albumin during the synthesis process of artificial antigen Cd-IEDTA-BSA (HSA) was analyzed using "fluorescence phase diagram", and the result shows that it was conformed to the "all-or-none" pattern. The polarization fluorescence spectra show that the microenvironments of tryptophan residues in carrier protein have some changes to cause changes in protein conformation.