Groundwater resources, both the quantity and quality, are vital to ecosystems and livelihoods in arid and semiarid regions. Natural and anthropogenic activities greatly impact groundwater quality and stability, posing a potential threat to the ecological environment. Using hydrochemical diagramming and stable isotope tracing, the hydrochemical properties, recharge sources, transformation processes, and driving mechanisms of groundwater-surface water (rivers) were evaluated for the period between 2004 and 2024 in an oasis-desert system of northwest China. The groundwater and surface water (rivers) were slightly alkaline, with pH ranges of 6.90-8.40, and 6.94-7.84, respectively. Compared to 2004, groundwater electrical conductivity (4097.08 mu S center dot cm-1) and total dissolved solids (2622.13 mg center dot L-1) increased in 2024, with salinization intensifying along groundwater flow paths. The surface water was mainly HCO-3-Ca2+ type, while the groundwater was SO2-4-Na+, Cl-- Na+, and Cl-- SO2-4-Ca2+-Mg2+ types. Abrupt changes in groundwater quality in oasis-desert systems were identified in 2009. The groundwater hydrochemical components were predominantly determined by cation exchange, rock weathering, and evaporation-crystallization. Mean values of delta 18O (delta D) in shallow and deep groundwater were-12.12 %o (-82.86 %o) and-11.84 %o (-83.59 %o), respectively. A close hydraulic connection exists between shallow and deep groundwater, thus pushing the latter to transform into shallow groundwater. Finite-element simulations indicate that as pumping rates increase and freshwater recharge decreases, groundwater quality deteriorates. The salinization range has expanded across the oasis-desert system, with the maximum distance extension toward the freshwater side reaching 26.32-55.26 %. Thus, it is recommended to control pumping rates to monitor groundwater deterioration.