To find the quick, convenient and sensitive method for detecting quantitatively the fumitremorgin B(FTB), three complex antigens were produced. First the hydroxyl group at C-6 position of FTB was reacted with hemisuccinate,forming the FTB-hemisuccinate(FTBS), then the compound was identified by ultimate and spectrometric analysis. The FTBS was combined with three carrier proteins respectively to form the amide compound. The preparating way and chemical structure of intermediate was analysed. Instead of ultraviolet absorption spectrometry, the infrared specteroscopy was used to detecting the complex antigens for the higher accuracy. Author's address Liu Jiang, Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Beijing 100050, PRC.