In this  study, ahigh  performance liquid chromatography -  tandemmass spectrometric    % HPLC- MS/  MS )metliod has    been  adopted   to  determine   malachite green   in      aquaculture  water.  Samples were subjected to extraction by dichloromethane，concentration and constant volume prior to HPLC - MS/MS analysis. The analysis was carried out in the multi    - reaction        monitoring    % MRM )    mode，and    internal  standard   isotope dilution  metiiod  was used     for    quantifica­tion. CalilDration curves for malachite green exhibited   good linearity over the   concentration range from   0. 25 to10.0 ng/mL，wit!i quantification limits of 0.01 ng/mL.     when the concentration degree was 0.   005 ?0. 100 ng/mL，the average recovery rate was 80% ~ 110%，and the relative standard deviation was less than 10% . It indicated that the metiiod can meet tiie requirements of detection of malachite green in aquaculture water. ' Chinese Fishery Quality and Standards，2015，5(3):34 -39]