Leaf traits reflect the adaptability of plants to their surrounding environment and their self-regulatory capacity. In this study, the leaf traits, and leaf δ¹³C and δ¹⁵N content of Nitraria tangutorum natural populations were determined along the precipitation gradient (from 300 to 40 mm) in seven experimental plots. The results showed the following. (1) With changes in precipitation gradient, the leaf width (LW), length to width ratio (LWR), leaf thickness (LT), leaf area (LA), specific leaf area (SLA), leaf nitrogen content (LNC), and leaf δ¹³C and δ¹⁵N content of N. tangutorum in the seven plots were significantly different (P < 0.05), but the difference in leaf length (LL) was not significant (P > 0.05). N. tangutorum adapted to the changes in the environment by regulating various functional traits of its leaves and forming optimum functional combinations of the traits. (2) There was a negative correlation between leaf δ¹³C content and leaf area (LA), and SLA, and positive correlation between leaf δ¹³C content and LNC; however, these correlations were not significant (P > 0.05). Only groundwater depth and leaf δ¹³C content showed a very significant positive correlation (P < 0.01). In the areas with precipitation < 100 mm, N. tangutorum mainly used groundwater sources, thereby becoming a hidden vegetation, which reduced its response to other environmental factors. (3) The LT and LNC can be used as leaf functional traits that reflect the difference in N. tangutorum among different regions. The data showed that LT was positively correlated with the annual average temperature (P < 0.05), especially on days when the annual maximum temperature was > 35℃ (P < 0.01). In high-temperature environments, LNC decreased significantly (P < 0.05), but LT and leaf δ¹⁵N content increased during this process (R²=0.62, P < 0.05). Therefore, the relative influence of LT and LNC on leaf δ¹⁵N content changed between arid and semi-arid regions, providing new insights to further explore the water limit threshold of desert vegetation in arid regions.