The immunolatex was prepared by covalent coupling. FTIR technology combined with substractive spectroscopy, deconvolution, derivation and curve-fitting methods were used to study the structure of the antibody protein on the immunolatex. The result demonstrates that the α-helix strcture of antibody increases with the increase in the pH value and the concentration of latex. So it is concluded that covalent coupling has a great impact on the secondary structure of antibody protein.