Abstract: Salix gordejevii (SG), a useful dune-fixing plant, is a pioneer bush that establishes primarily on the margins of moving sand dunes in Horqin Sand Land and Hunshandak Sand Land, Inner Mongolia, China. In this study, the heat and drought tolerance of SG were examined and compared to S. babylonica (SB). Leaves removed from the two species were subjected to six temperature treatments (25, 30, 35, 40, 45, 50 ℃) for 60 minutes and six drought treatments (0, -0.25, -0.5, -0.75, -1.0, -1.25 MPa) for 24 hours. The relative water content, membrane permeability and maximal quantum efficiency of photosystem II (PSII) were assayed. Leaves of SG maintained more water during both temperature and drought treatments. Temperature treatments below 45 ℃ had no effect on the membrane permeability of either of the two species, but treatments above 45 ℃ induced much higher electrolyte leakage in SG than in SB. Each drought treatment caused an increase in membrane permeability in both SG and SB but was greater in SB in all drought treatments. Temperatures below 35 ℃ did not influence maximal quantum efficiency of PSⅡ (measured as Fv/Fm) in either of the two species, whereas treatments above 40 ℃ caused Fv/Fm to decrease in both species but was significantly lower in SG. Drought treatments resulted in a decline in Fv/Fm in both species but declines were significantly higher in SG when the osmotic potential was lower than -0.75 MPa. These results suggest that SG has a higher capacity for drought tolerance and a lower capacity for heat tolerance compared to SB. The different stress tolerance between SG and SB was due mainly to different sensitivities of electron transport through PSII to heat and drought.