Abstract: 1.000 0 g of the crushed sample was added into 20 mL of 0.15 mol·L^-1 nitric acid solution, and the mixture was placed at room temperature for 12 h, then extracted at 85℃ for 1.5 h. After extraction, the mixture was cooled to room temperature and centrifuged at 8 000 r·min^-1 for 15 min, and the supernatant was filtrated through 0.45 μm organic membrane. Arsenite, arsenate, arsenic, arsenobetaine, monomethyl arsenic and dimethyl arsenic were separated on an AS7 anion column (4 mm×250 mm), with 5 mmol·L^-1 ammonium carbonate solution and 100 mmol·L^-1 ammonium carbonate solution as the mobile phase for gradient elution, and determined by ICP-MS. The linearity range of arsenic in the six species was same 1.0-10.0 μg·L^-1, and the detection limits (3s) were 0.108, 0.055, 0.027, 0.053, 0.011, 0.108 μg·L^-1, respectively. Values of recovery obtained by standard addition method ranged from 91.7% to 105%. The relative standard deviations (n=6) of the measured values ranged from 1.7% to 4.5%.