<p>Surface water resources are severely limited in the Ordos Coal Mine Base, northwest China, making groundwater a critical resource for meeting production, domestic, and ecological water demands. Despite its importance, regional− scale assessments of groundwater quality in this area are scarce. To solve this problem, we adopted a comprehensive method combining self− organizing map (SOM) and principal component analysis (PCA) to systematically analyze 69 groundwater samples collected near 14 mining areas in 2023. We focused on analyzing hydrochemical parameters such as the eight major ions, TDS, fluoride ions, and pH, and explored the hydrochemical characteristics and types. Hydrogen and oxygen isotopes were used to identify the main groundwater sources, and groundwater samples in the study area were evaluated for water quality and health risks. The groundwater samples were categorized into three clusters: C1 (SO₄− Ca and Cl− Ca types, primarily associated with high hardness); C2 (a mixture of HCO₃− Na, mixed, and SO₄− Na types, largely linked to elevated fluoride levels); and C3 (predominantly Cl− Na type, correlated with high salinity). Groundwater is primarily recharged by atmospheric precipitation. Drinking water quality predominantly falls into Grade IV to V. Health risk assessments indicate that the groundwater in the region poses a generally moderate level of health risk. This study supports informed groundwater management strategies in the Ordos Coal Mine Base and provides a regional− scale framework for coal mine groundwater quality investigations.</p>