Hydrochemistry is a critical indicator of water quality. We analysed 146 hydrochemical parameters of groundwater and the hydrogeological background of the Kashi region in China, examined their spatial distributions, and elucidated the mechanisms of their occurrence. We used graphical and multivariate statistical methods to distinguish between high- and poor-quality water. In the Kizil-Cakmak River Basin of the northern Kashi region, the primary cations were Ca2+ and Mg2+, and the primary anion was SO42−; their concentrations were four times higher than the Class III water quality standard. Additionally, the salinity was high. In contrast, in the upstream and midstream parts of the Gez-Kushan River Basin in the southern Kashi region, the primary ions were HCO3− and SO42−, and the salinity was low. Downstream of the Gez-Kushan River Basin, the primary ion was Cl−, and the salinity was low. There was a wide-ranging spatial variability in the SO42−, Cl−, and Ca2+ contents throughout the study area. The present findings can be applied to locate suitable domestic, agricultural, and industrial water sources in the Kashi region and can provide theoretical guidance for the scientific development and management of groundwater in this region.