Abstract: Malachite green(MG), leucomalachite green(LMG), crystal violet(CV) and leucocrystal violet(LCV) residues in fishes were determinated using ultra-high performance liquid chromatography-mass spectrometry(UPLC-MS/MS). Samples added with internal standard were firstly extracted and centrifuged in acetonitrile, and then degreased through neutral alumina column, dried in nitrogen, volumed by solution of acetonitrile 5 mmol/L ammonium acetate （50∶50，V/V). MG, CV and their metabolites have great linearity relationship in the concentration range of 4.0 μg/L The detection limits of MG， LMG and CV are 0.01 μg/kg, and the LVC is 0.06 μg/kg. Method recovery is made by addition of 2.0 μg/kg internal standard solution and mixed standard solution at concentration levels of 0.25 and 2.0 μg/kg， respectively. The results show that average recoveries are between 81.4% and 97.8%, and relative standard deviations(RSD, n=6) are between 5.9% and 11.2%. These four substances in 109 batches fish samples are detected in different degrees. This method is sensitive and reliable, which can provide reference for market regulators in aquatic fish products breeding, using and circulation.