Abstract: Based on the existing basic geological and hydrogeological data of the study area as well as hydrochemical data, the paper uses multiple methods including mathematical statistics, Schukalev classification, Piper diagram, Schoeller diagram, Gibbs diagram and ion ratio analysis to analyze the hydrochemical characteristics of groundwater in different areas of alluvial-proluvial fan, discusses the main controlling factors of groundwater evolution in different areas, and studies the status of groundwater environmental pollution. The results show that the groundwater in alluvial-proluvial fan of Taizi River is weakly affected by human activities, with the main hydrochemical types of HCO₃·SO₄-Ca and HCO₃·SO₄·Cl-Ca in the root fan, HCO₃-Ca and HCO₃·SO₄-Ca types in the mid-fan and HCO₃-Ca type in the end fan. The intensity and mode of rock weathering and ion exchange are various during groundwater evolution in different parts of Taizi River alluvial-proluvial fan. The nitrogen pollution in the groundwater is mainly affected by mining and metallurgical activities, chemical industry and agricultural activities, and its spatial distribution is closely related to human activities. The analysis and research on the hydrochemical types and characteristics, hydrochemical genesis of groundwater and the present situation of nitrogen pollution in Taizi River alluvial-proluvial fan can provide scientific basis for further exploitation and sustainable development of groundwater sources.