A method for the simultaneous determination of 3 β-agonists in animal manure was studied by ultra high performance liquid chromatography coupled with electrospray ionization triple-quadruple tandem mass spectrometry(UPLC-ESI MS/MS).The drugs were cleaned up with perchloric acid solution after enzymolysis and adjusting pH to alkaline.The purified analyte was extracted with ethyl acetate.The extract was evaporated to dryness under nitrogen,and reconstituted in mobile phase solution.The target compounds were confirmed and quantified by UPLC-ESI MS/MS with the internal standard method.Under the optimal conditions,the calibration curves of 3 β-agonists showed good linearities in the range of 0.5-20.0 μg/L with correlation coefficients more than 0.998.The average recoveries of 3 β-agonists were in the range of 80.3%-110.2%,and the relative standard deviations(RSDs) were 3.0%-7.7%.The limits of detection(S/N=3) ranged from 0.04 μg/kg to 0.07 μg/kg.