Objective A method for the quantitative analysis of eight kinds of nitroimidazoles and their metabolites in milk by ultra-performance liquid chromatography-tandem mass spectrometry coupled with simple protein precipitation was established. Methods One gram milk sample was precipitated by trichloroacetic acid, and then stratified by high-speed centrifugation. The middle layer of the supernatant was filtered through a hydrophilic polytetrafluoroethylene membrane. The analytes were separated on a Hypersil GOLD C18 column (100 mm×2.1 mm, 1.9 μm), and detected in selected reaction monitoring (SRM) mode via positive electrospray ionization. The matrix matching and internal standard method was used for quantification. Results The nitroimidazoles and their metabolites showed good linearity in the range of 0.3-10.0 ng/ml, and correlation coefficients were above 0.998 5. The limits of detection of the nitroimidazoles and their metabolites in milk were between 0.1 and 0.2 μg/kg. The recoveries at spiked levels of 0.5,2.0 and 5.0 μg/kg were within 83.6%-111.8%, the intra-day relative standard deviation(RSD)were within 2.7%-9.1%, and the inter-day RSD were within 1.0%-9.3%. Conclusion The method was accurate, fast, cheap, easy, and could satisfy the requirements of high-throughput monitoring nitroimidazoles in milk.