A method was developed for the determination of fumonisin B1(FB1) and fumonisin B2(FB2) in cereals by high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS).The sample was extracted with methanol-water-acetic acid(74∶25∶1),and cleaned up by strong anion exchange column(SAX).FB1 and FB2 were completely separated on a ZORBAX Extend-C18 column(150 mm×2.1 mm，1.8 μm) with gradient elution by using 0.1% acetic acid water solution-acetonitrile as mobile phase,and detected by positive ion electrospray ionization mass spectrometry(ESI-MS) under select reaction monitoring(SRM) mode.The results showed that the linearities of FB1 and FB2 were in the concentration ranges of 2.5-1 000 μg/L,5.0-1 000 μg/L,respectively,with correlation coefficients of 0.999 5 and 0.999 7,respectively.The average recoveries of FB1 and FB2 from four kind of blank matries at three spiked levels of 0.02,0.50,2.00 mg/kg were in the range of 67.5%-90.5%and 70.5%-95.3%,respectively, with relative standard deviations(RSDs,n=5) of 1.3%-11.4% and 1.5%-10.6%,respectively.The limits of detection were 2.00 μg/kg for FB1and 4.00 μg/kg for FB2.This method was stable,reliable,and could be used for detection of FB1 and FB2 in cereals simultaneously.