Abstract: A method was established to determine five arsenic species in seafood using high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Freeze dried samples were extracted with methanol-water (3:1) shaking in 70 ℃ water bath for the first time, and extracted with methanol-water(1:1) for the second and third time. Then we separated the extract by anion exchange column using 20 mmolL-1 NH4HCO3+NH2COONH4 mobile phase, and detected the compounds with plasma mass spectrometry. The detection limit and quantification limit of five arsenic speciations in seafood varied from 0.057~0.13 gL-1and from 0.19~0.43 gkg-1.The average recovery of five species arsenic spiked in tested samples at 3 levels ranged from 83.2%~115% with the relative standard deviation (RSD) between 2.15% and 9.97%. The proposed method had been applied to the analysis of seafood came from Australia, indicating that arsenobetaine (As B) and dimethylarsinic acid (DMA) were main species of arsenic in seafood, and the extraction efficiency of five arsenic speciations were more than 90%, which was higher than of total arsenic .