A comprehensive method was developed and optimized for the simultaneous analysis of sulfonamides,quinolones,steroid hormones and tetracycline by ultra performance liquid chromatography-mass spectrometry(UPLC-MS).The veterinary drugs in milk samples were extracted with 5% acetic acid-acetonitrile solution,and then the mixture was centrifuged.The supernatant was purified with an HLB solid phase extraction column,and analysed by UPLC-MS and quantified by the external standard method.Average recoveries of 25 veterinary drugs at three spiked levels ranged from 61.6% to 119.2% with relative standard deviations(RSDs) of 2.5%-13.4%.The method limits of detection(LOD) for target compounds were in the range of 0.5-2.0 μg/kg.