Abstract: The 4 arsenic species ［As(Ⅲ), As(Ⅳ), MMA and DMA］in ground water were simultaneous determined by anion exchange chromatography coupled with inductively coupled plasma mass spectrometer. The 4 arsenic species were separated on an IonPac AS14 anion exchange column successfully within 15 min using IonPac AG14 anion guard column, with ammonium bicarbonate as mobile phase for gradient elution. Under 25 μL of injection volume, the linearity ranges of the 4 arsenic species were 0.50-200 μg·L-1, with detection limits in the range of 0.03-0.06 μg·L-1. Recoveries obtained by standard addition method were in the range of 97.0%-102%. The proposed method was applied to analysis water samples, giving results in constant with those obtained by ICP-MS.