Abstract: The photosynthetic characteristics (using the CI-340 photosynthesis mensurate system) and other physiological indexes of Elymus dahuricus under different saline-alkaline grassland conditions were determined at different growth stages. With an increase of saline-alkaline concentration, the net photosynthetic rate, transpiration rate, stomatic conductance and intercellular CO₂ concentration decreased. Net photosynthetic rate at light (L) and moderate (M) salinity was the largest in July, but the largest net photosynthesis at high (H) salinity was in August. At different months and different saline-alkaline grassland conditions, net photosynthesis was affected by both stomatal limitations and non-stomatal limitations. The content of soluble sugar, MDA and Pro all increased with increased saline-alkaline conditions. MDA content was largest at the seedling stage, but it reduced with the growth of E. dahuricus. The increase of Pro and soluble sugars of E. dahuricus at the seedling and heading stages can reduce seedling damage from salt stress.