Plant functional traits can reflect the adaptation of plant species and their ecological strategies to surrounding environment. Populus euphratica is an ecological key species of desert ecosystem playing an irreplaceable role in climatic regulation, biodiversity conservation, and maintaining the desert ecosystem stability and Oasis ecological security. Studying the relationships between leaf functional traits of desert plants and their responses to environmental changes helps to better understand the trade-off patterns of traits and adaptation strategy to extreme drought, then provides a theoretical basis for the population protection and restoration of fragile desert ecosystem. In this study, we explored how leaf functional traits and soil factors responded to groundwater depth (GWD), and examined the relationship between leaf functional traits and soil factors in Tarim extremely arid area, in order to reveal soil factors that influencing the functional traits and the adaptation strategies of P. euphratica to arid desert environment. The experiments were carried out at twelve sampling points with different GWDs in the upper reaches of Tarim River, Xinjiang Autonomous Region, northwestern China. Six leaf functional traits of P. euphratica individuals, soil factors, and the GWD in each plot were measured. The leaf functional traits and soil factors in different habitats (different groundwater depths) were analyzed and the relationship between these traits and soil factors were discussed combining with Pearson correlation, stepwise regression, and redundancy analysis. The results show that: (1) there were significant differences in leaf functional traits of P. euphratica under different GWD habitats (P<0.05), the specific leaf area (SLA), leaf width (LW), and leaf area (LA) decreased, while the leaf length (LL), leaf dry matter content (LDMC), and leaf tissue density (LTD) increased with the increase of GWD (P<0.05). The leaf functional traits of P. euphratica exhibited different degrees of variation, with the higher coefficient of variation of LW, LA (48.6%, 39.4%) which were more sensitive to GWD changes. (2) The soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and nitrogen phosphorus ratio (N/P) in shallow GWD habitats were significantly higher than those in deep GWD habitats (P<0.05), while the carbon nitrogen ratio (C/N) was the opposite. Among them, the coefficient of variation of TN, SOC, and N/P were high (≥40%) which were more sensitive to GWD changes. (3) Stepwise regression and redundancy analysis revealed that soil environmental factors including C/N, N/P, TN, and SOC had the higher influence, and could better explain the leaf functional traits variation of P. euphratica. The C/N of soil significantly affected LW, LA and SLA, the N ∶ P significantly affected LL and LDMC, and TN significantly affected LTD of P. euphratica leaves (P<0.05). (4) With the increase of GWD, the nutrients of soil pool decreased and the forest soils became arid and barren. In order to survive, P. euphratica adopted the ecological strategy, such as reducing LW, LA, and SLA, increasing LL, LTD and LDMC, which were beneficial to enhance resilience, to adapt the arid barren desert environment. The study indicates that P. euphratica adapts to extremely arid environment by forming synergistic trade-offs between leaf functional traits. Soil C/N, N/P, and TN are the most critical soil factors affecting the leaf functional traits of P. euphratica. The findings of the study provide a scientific guideline for conservation, rejuvenation of P. euphratica forest and restoration of desert vegetation in Tarim extremely arid area.