Abstract: LC-MS/MS was applied to the determination of nitroimidazoles (metronidazole;ronidazole;dimetridazole;tinidazole and ornidazole) in poultry feed.Nitroimidazoles in poultry feed were extracted with a mixed solution of ethyl acetate and 5 g·L-1 Na2CO3 solution,and the organic phase obtained was evaporated to dryness.The residue was desolved with 0.1 mol·L-1 phosphoric acid,and purified by HLB SPE column.The eluate in acetonitrile was used for LC-MS-MS determination,in which C8 column was used as chromatographic column,and a mixture of methanol and water was used as mobile phase in gradient elution;positive electrospray ionization as well as multiple reaction monitoring mode was used in the detection.Linearity ranges of 5 nitroimidazoles were found between 10-500 μg·L-1 with their detection limits (3S/N) of 10 μg·kg-1.Values of recovery found by standard addition method were in the range of 79.4%-91.3%,and values of intra-batch and inter-batch RSD′s (n=6) found were in ranges of 5.5%-13.9% and 6.7%-18.2% respectively.