A high performance liquid chromatography-inductively coupled plasma-tandem mass spectrometry(HPLC-ICP-MS/MS) was developed for the simultaneous determination of six arsenic species,i.ep-arsanilic acid(p-ASA),roxarsone(ROX) and their degradation products arsenite(As(Ⅲ)) and arsenate(As(Ⅴ))(inorganic arsenic),monomethylated arsenic(MMA) and dimethylated arsenic(DMA) in soils.The soil samples were extracted with 0.1 mol/L NaH2PO4-01 mol/L H3PO4(9∶1,by volume) as extraction solvent at a liquid to solid ratio of 50 mL/g,by microwave assisted extraction at 80 ℃ for 30 min.Five arsenic species in the extracts were well separated within 15 min on a Hamilton PRP-X100 anion exchange column(250 mm×4.1 mm，10 μm) using 60 mmol/L(NH4)2HPO4 containing 5% methanol(pH 6.0) and water as mobile phases by gradient elution.Under the optimized conditions,there were good linear relationships for the analytes in the concentration range of 0-500 μg/L with their correlation coefficients(r2) not less than 0.999 1.The limits of detection were 0.043-0080 μg/kg for the analytes，and the relative standard deviations ranged from 1.7% to 3.8%.The method was applied in the analysis of three soil samples,and recoveries for the analytes were in the ranges of 71.6%-106%.The developed method is simple,rapid,accurate and reliable,and is suitable for the determination of arsenic species in soils.