Abstract: Songnen Plain is an important productive base of commodities in China,but its groundwater environment is ever deteriorating due to the impacts of the global climate changes and the excessive high human activities,and it become the important factor restricting the eco-environmental construction and the socio-economic development. This paper takes the Taoer River basin as the typical study case,and the groundwater samples are analyzed scientifically and systemically,then the descriptive statistics,the correlation matrices,the ratio coefficient of the main ions and the piper diagram are used to gain the better understanding of the spatial and the temporal variation of the hydrochemistry characteristics and the evolution laws of groundwater.The following main hydro chemical processes are inferred to controll the water quality of the groundwater system: (1)the weather-dissolution,(2)the evaporative condensation,(3)the ion-exchange reactions,and(4)the mixing of the surface water with high salinity. All conclusions can offer the scientific guidance for the sustainable development and the management of water resources in Songnen Plain,Northeast China.