This study established a method for the simultaneous detection of 19 β-agonist veterinary drug residues in milk samples. The samples were extracted with acidified acetonitrile solution, and the phospholipids were removed by using an Oasis PRiME HLB solid-phase extraction cartridge. The analytes were detected by ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Under optimized pretreatment and instrumental conditions, all analytes showed a good linear relationship in the concentration range of 0 to 10 ng/mL (R2 ≥ 0.995). The average recovery rates for milk samples spiked at levels of 0.2 to 1.0 μg/kg were between 70% and 110%, and the precision relative standard deviation (RSD) was less than 15%. The method had the advantages of simple and fast pretreatment, and high sensitivity and stability, and therefore could be used for the rapid detection of β-agonist veterinary drug residues in milk.