A method was developed for the determination of hexabromocyclododecanes（HBCDs） in marine organisms by high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS） coupled with LC-Si SPE clean up.The samples were extracted with n-hexane,cleaned up by LC-Si SPE,and analyzed by LC-MS/MS.The major parameters affecting LC-Si SPE eluting conditions were also investigated.The chromatographic separation was performed on an ACQUITY UPLC BEH C18 column by gradient elution with water and methanol-acetonitrile solution（methanol∶acetonitrile=4∶6） as mobile phase.The detection of analyte was carried out by electrospray mass spectrometry in negative ionization under multiple reaction monitoring mode,and the internal standard method was used for quantification.There existed good linear relationships for HBCDs in the range of 0.50-100.0 μg/L with correlation coefficients（r2） more than 0.995.The quantitation limits of the method were 0.20 μg/kg.The recoveries for HBCDs were in the range of 85.6%-97.3%,with relative standard deviations of 3.9%-8.8%.Therefore,the method could be applied in the identification and quantitation of HBCDs in marine organisms with low matrix interference and good reproducibility.