Groundwater plays an irreplaceable role in ensuring the daily lives of urban and rural residents, supporting socio-economic development, and maintaining ecological balance in northern Qinling Mountains. This chapter investigates the hydrochemistry and quality of groundwater in the northern Qinling Mountains. The groundwater chemical characteristics, formation mechanisms, and quality assessment were systematically analyzed to address growing concerns over water scarcity and pollution. Results reveal that the groundwater is predominantly of the HCO3-Ca⋅Mg type, with rock weathering identified as the primary controlling factor. Key findings include higher ion levels near the Wei River, and elevated nitrate in agricultural areas due to human activities. The Entropy-Weighted Water Quality Index (EWQI) evaluation indicates that 89% of samples meet the drinking water purpose, though localized pollution exists.