As one of the most important water sources, groundwater has been significantly affected by human activities. The study of chemical characteristics and formation mechanism of groundwater is of great significance for the rational utilization of groundwater resources. Various types of aquifers are distributed in Yinan, East Wenhe River basin where agriculture and aquaculture are well- developed. Therefore, this area is ideal for the study of formation and groundwater hydrochemistry under the influence of human activities. The Piper diagram, ion ratio method, mathematical statistical methods (correlation analysis, factor analysis, cluster analysis) and other methods are used to study the groundwater hydrochemical characteristics and formation mechanism in the study area. The results show that the groundwater hydrochemical types are mainly HCO 3- Ca and HCO 3- Ca·Mg, and the TDS content is between 243 and 1473 mg/L. The HCO- 3, SO 2- 4, Ca 2+and Mg 2+ in groundwater mainly come from the dissolution of carbonate and sulfate minerals, while Na+, K+, Cl- and NO- 3 mainly come from the dissolution of halite and pollution by human activities. The effect of water- rock interaction on groundwater hydrochemistry exceeds 62. 024%. The number of groundwater samples with obvious influence of human activities accounts for 13. 6% of the total groundwater samples, and the contribution of anthropogenic impacts to groundwater hydrochemistry reaches 20. 318%. The river valley plain is obviously polluted by human activities such as agriculture and aquaculture.