Abstract:A method based on high performance liquid chromatography tandem mass spectrometry（HPLC-MS/ MS）has been developed for the determination of 18 β-agonists residues in beef.The analytes were extracted with ammonium acetate solution and hydrolysised with beta-glucuronidase overnight.After being cleaned up with column，concentrated and reconstituted，the analytes were separated by HPLC with an Thermo Hypersil Gold column（2.1 mm×100 mm，3 μm）under the mobile phase containing 0.1 % formic acid and acetonitrile. Identification and quantification were achieved by HPLC-MS/MS with multiple reaction monitoring（MRM）via positive-ion mode.The method showed good linearity in the range from 0.5 μg/kg to 10 μg/kg，The limit of quantitation of all β-agonists were 0.5 μg/kg. The overall recovery varied from 68.5 % to 91.9 % at the spiked level of 0.5，1.0，2.5 μg/kg and the relative standard deviation of the method varied from 4.2 % to 13.2 %.The method is sensitive，reproducible，simple and economic，the method adapts to the determination of β-agonists residues in beef.