Stomatal regulation is a key way for plants adapting to changes in water condition. Therefore, it is important to understand the response of stomatal behavior in Populus euphratica seedlings to varying sediment type and groundwater depth. The newly formed flood plain is the natural habitat for P. euphratica recruitment, and its sediment type and groundwater depth are highly heterogeneous in time and space. Previous studies have mainly focused on the physiological and ecological response of P. euphratica to the change of groundwater depth. However, the affects of the interaction between sediment type and groundwater depth changes on the plant-water relationship are well understood.This study was carried out at the Akesu National Station of Observation and Research for Oasis Agro-ecosystem. The tested P. euphratica seedlings were two-yearold, transplanted from the flood plain of the upper reaches of the Tarim River in June 2020. P. euphratica seedlings were grown in lysimeters to examine the interactions between soil texture and groundwater depth on stomatal behavior. Each factor included 3 treatments, sandy soil (S₁), sandy loam (S₂), clay loam(S₃) for soil texture, and 30 cm (W₁), 60 cm (W₂), 90 cm (W₃) below soil surface for groundwater. Stomatal conductance (G_S), stomatal conductance slope (g₁), and stomatal limitation to photosynthesis (L_S) of P. euphratica seedlings under each treatment were obtained during growing season in 2020. The results showed that (1) the response of stomatal behavior in P. euphratica seedlings to alterations in groundwater depth was mediated by sediment type. (2) G_S was significantly different between soil textures under the same groundwater depth, with the G_S values for S₂ and S₃ higher than under W₁, S₁ and S₂ lower than S₃ under W₂, and increasing from S₁ to S₃ under W₃. (3) The largest g₁ occurring at S₁, followed by S₂ and S₁ under the same groundwater depth. (4) The differences in L_S between soil texture varied with groundwater condition, with the values in S₂ and S₃ significantly higher than S₁ under W₁, and under W₂ and W₃, the largest occurring in S₂, followed by S₃ and S₁, respectively. In conclusion, the response of stomatal behavior in P. euphratica seedlings to groundwater depth was mediated by soil texture, which can be attributed to the effects of soil texture on the development of root system and the vertical distribution of soil water. Thus, sediment type may be a major factor that affects plant-water relationship in early life history for P. euphratica.