Abstract: An immunoaffinity detection method for simultaneously determining the aflatoxins B₁,B₂,G₁ and G₂ in tobacco and tobacco products was developed via solvent extraction of sample,purifying and concentrating on immunoaffinity column,pre-column derivatization by trifluoroacetic acid,separation by HPLC,and detection by fluorescence detector.The results showed that:1) The determination could be completed within 20 minutes,the four target aflatoxins were well separated and exhibited good linear relations with correlation coefficients r>0.99.2) The recoveries of the method ranged from 85% to 117% with the relative standard deviation(RSD) of 0.2%-9.4%(n=6),and the limits of detection and quantification of aflatoxin B₁ were 0.10 and 0.34 μg/kg,respectively.