Objective To understand the variation of arsenic concentration in underground water at the endemic arsenic poison disease area of Jianghan Plain so as to better understand the spatial distribution of high arsenic groundwater,hydro-chemical evolution and source of arsenic in this region.Methods Thirty underground water samples were collected respectively around 3 km radius of the two houses where arsenic poisoning patients lived,in Xiantao and Honghu.Sediment cores of three drillings were collected as well.Both paired t-test or paired Wilcoxon Signed Ranking Test were used to compare the arsenic concentration of water.Results The arsenic concentration in 2011-2012 appeared lower than that in 2006-2007 at the Nanhong village of Xiantao (t=4.645 3,P＜0.000 1),but was higher(S=-150,P＜0.000 1) in the Yaohe village of Honghu.The pH value showed weak acidity with Eh as weak oxidated.Positive correlations were observed between arsenic concentration and C1,HCO3-,Fe,Mn.However,negative correlations were found between As and SO42-,NO3-.The range of arsenic content in the sediment was 1.500 mg/kg to 17.289 mg/kg.The maximum arsenic content existed in the soil layer,while the minimum arsenic content existed in the sand layer.Conclusion The concentration of arsenic varied widely with time and space at endemic arsenic poison disease area of Jianghan Plain.Characteristics of these water chemicals showed significant differences,when compared to the groundwater from Datong Basin,Shanxi Shanyin and Hetao Plain of Inner Mongolia,which presented a typical environment with high arsenic contents in the groundwater.The arsenic content in the sediment samples seemed related to the lithologic structure.