A method for simultaneous determination of 23 sedative residues in aquaculture water by isotope dilution liquid chromatography tandem mass spectrometry(LC-MS/MS) was established. The samples were filtered by 0.45 μm filter membrane， purified by solid phase extraction column(Oasis HLB column)， then concentrated the eluate and brought to volume with 50% methanol 50% water. By using 1% formic acid aqueous solution and acetonitrile as mobile phase， the targets were separated by an Agilent InfinityLab Poroshell 120 SB-C18 chromatographic column， and determined in multi reaction monitoring mode and quantified by internal standard method. The results showed that the linearity of 28 sedatives was good in the concentration range of 0.5～100 ng/L (r > 0.99)， and the detection limits and quantitative limits were 0.1～0.3 and 0.4～1.0 ng/L， respectively. The average recovery was 73.5%～117.6% and the relative standard deviations(RSD) were 1.1%～ 9.9%. This method has simple pretreatment， good purification effect and high sensitivity. It can be used for the rapid detection of 23 sedative drug residues in pond aquaculture water.