The ceftiofur artificial antigen was synthesized by conjugating ceftiofur to BSA with n hydroxysuccinimide and N,N dicyclohexyl carbodiimide.The synthesis product was characterized by the traditional sodium lauryl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE） and electrospray ionization mass spectrometric（ESI MS） method.The result showed that the ceftiofur artificial bovine serum albumin antigen was succesfully prepared and the binary complex ratio of ceftiofur to BSA was about 8.Herein,atomic force microscope（AFM） was firstly used to characterize the ceftiofur artificial antigen.