Plant functional traits, defined as morpho-physio-phenological traits, reflect the response and adaptation of plants to the environment, and function as a bridge between the plant and environmental factors. In this study, we explored how leaf functional traits responded to groundwater depth (GWD) and their interactions of P. euphratica growing in different arid habitats, and examined the relationship between leaf functional traits and groundwater depths in Tarim extremely arid area, in order to reveal the potential ways of P. euphratica in adapting arid desert environment. The experiments were carried out at eight sampling points (50 m×50 m) with different GWD in the upper reaches of Tarim river, Xinjiang Province, northwestern China in the summer 2019. Seven leaf functional traits of ten P. euphratica individuals in each plot with stem base diameter (BDH)>10 cm were measured, and the GWD and soil moisture of each plot were measured. We then carried out one-way ANOVA and Duncan tests to assess differences in leaf functional traits (specific leaf area, SLA; leaf area, LA; individual lamina mass, LDM; leaf water content, LWC; leaf thickness, LT; leaf dry mass content, LDMC; and leaf tissue density, LTD) under eight GWD. Pearson correlation and the stepwise regression were conducted to determine the quantitative relationships between leaf functional traits and GWD. The results showed that seven leaf traits varied in varying degrees from 9.02% to 40.02%, while the maximum and minimum coefficient of intraspecific variation were LA and LWC, LDMC, respectively. The leaf traits showed large variation along groundwater depth gradient. The leaf functional traits had significant difference in the eight groundwater depths, and were extremely significant correlation with GWD (P<0.01). LA, SLA, and LWC were positively correlated with LDM (P<0.01), but negatively correlated with LT, LTD and LDMC (P<0.01). LDMCs were positively correlated with LT and LTD, and LWCs were positively correlated with LA and SLA (P<0.01), which indicated that P. euphratica adapted to the harsh desert environment through mutual adjustment and trade-off with leaf functional traits. Stepwise regression analysis showed that LA and LT were the most sensitive to the change of GWD, and they could be used to indirectly diagnose the change of GWD in arid desert area. The SLA, LA, LDM, and LWC of P. euphratica declined, on the contrary, the LT, LTD and LDMC increased with GWD decreasing, which indicated that P. euphratica had changed from development strategy with high growth rate and resource utilization to conservative strategy with enhancing nutrient storage and defense ability, broadening its ecological amplitude and enhancing its fitness in desert adversity. In brief, P. euphratica formed trait combination with series of functional traits in extremely arid area, such as smaller LA, SLA, LDM and larger LDMC, LTD, LT, which were beneficial to reduce water loss, store nutrient and enhance drought tolerance. This may be its main ecological strategy for adapting to arid and barren environments.