A method was developed for the simultaneous determination of arsenic acid \[As(Ⅴ)\], arsenious acid \[As(Ⅲ)\], arsenobetaine (AsB), monomethyl arsonic acid (MMA) and dimethylarsinic acid (DMA) in aquatic animals and their products by high performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The extraction reagent was 0.15 mol/L nitric acid with heat-assistant condition for 30 min at 80 ℃. Then, the five arsenic species were separated by a anion exchange column (Hanmilton PRX-X100 250 mm×4.1 mm, 10 μm) and detected by ICP-MS. The effects of different elution methods on the separation of five arsenic forms were compared, and the chromatographic conditions on the separation of arsenic were studied and optimized. The recoveries of the five arsenic species spiked in aquatic animals at three levels ranged from 87.8%～97.5%, and the relative standard deviations (n=6) were 1.5%～4.5%. The five arsenic species showed good linearity in the range of 0～100 μg/L, and the limits of detection for the five arsenic species were 0.002～0.010 mg/kg. This method was simple, accurate and durable for the detection of arsenic species in aquatic animals and their products.