A high performance liquid chromatography-tandem mass spectrometric（HPLC-MS/MS） method was established for the determination of ciguatoxin in deep sea fish．The residues in fish were extracted with methanol-hexyl hydride（4∶1），and purified by an HLB SPE column.The detection of ciguatoxin was performed by mass spectrometry with electrospray in positive ionization mode and multiple reaction monitoring（MRM） mode.No significant matrix effect was found for the spiked samples after purification．The recoveries of ciguatoxin in food were in the range of 70%-84% at spiked levels of 0.01-0.1 μg/kg．The relative standard deviations（RSDs） were less than 7%．The limits of detection（LOD） and the limits of quantitation（LOQs） were 0.01 μg/kg and 0.02 μg/kg，respectively．This method was simple,rapid and reliable,and could meet the requirement for determination of ciguatoxin in deep sea fish．