A liquid chromatography-tandem mass spectrometric(LC-MS/MS) method was developed for the simultaneous determination of olaquindox(OLQ) and carbadox(CBX) in animal originated foods(pork,chicken and fish).The CBX and OLQ were extracted with 0.1 mol/L sodium dihydrogen phosphate(NaH2PO4) solution(pH 6.0) and cleaned up with solid-phase extraction Oasis HLB column.The separation of compounds was carried on a Waters Xterra MS C18 column(5 μm,150 mm×2.1 mm) by gradient elution using acetonitrile-0.2%formic acid as mobile phase.The analyte was detected by tandem mass spectrometry under multiple reaction monitoring(MRM) mode with positive electrospray ionization.The CBX and OLQ were quantified by the matrix-matched external standard method.The results showed that the calibration curves of CBX and OLQ were linear in the range of 1-20 ng/mL with correlation coefficients of 0.998 1-0.999 9.The average recoveries of CBX and OLQ at spiked concentration levels of 0.2,0.4,2.0 μg/kg ranged from 70% to 93% with relative standard deviations(RSDs) of 1.9%-16.7%.The limits of quantitation(LOQ,S/N≥10) for two compounds were both 0.2 μg/kg.The established method was used for the determination of real samples(including pork,fish,chicken samples) and the result was compared with that of the national standard method.The result showed that the method was sensitive and accurate,and was suitable for the determination and confirmation of olaquindox and carbadox in pork,chicken and fish samples.