Abstract：A hapten 6-[(1-naphthyloxy) carbonyl] amino hexanoic acid (CNH) completely preserving the carbamate group was synthesized with aminohexanoic acid and 1-naphthol, which was activated with 4-nitrophenyl chloroformate. Then the CNH hapten was covalently attached to carrier protein by utilizing the modified active ester method to synthesize antigen. Some factors influencing synthesis of CNH antigen were studied, and the conditions were optimized through orthogonal design experiments. A series of CNH-BSA antigens of different CNH/BSA mole ratios were synthesized by altering the experimental conditions. The antigens were identified with the UV-VIS and IR analysis.