Abstract: To investigate the hydrochemical characteristics and formation mechanism of shallow groundwater in the around-lake area of Poyang Lake,14 indicators of 242 groups of groundwater samples were analyzed by Piper diagram,cluster analysis and iron ration analysis.The results showed that the groundwater belonged to the weakly acidic fresh water with low total hardness;Ca2+ was the dominant cation in groundwater,HCO3- was the dominant anion.Piper diagram showed that the hydrochemical types of groundwater were mainly HCO3-Ca,HCO3-Ca·Mg,HCO3-Na·Ca and HCO3·Cl-Na·Ca.Cluster analysis and ion ration analysis showed that the groundwater chemical compositions were mainly affected by rock weathering and dissolution,partly affected by evaporation-concentration and cation exchange.