Abstract: In order to study the effect of salt alkali stress on physiological indicators of alpine grass seedlings and provide scientific basis for grassland ecosystem function, hydroponics was used to investigate the effects of different salt alkali concentrations and temperature conditions on the growth and physiological indicators of four alpine grass seedlings.The results showed that: ①With the increase of saline alkali concentration, the soluble sugar content of the four alpine forages showed an increasing trend. The effect of temperature on the soluble sugar content of seedlings was extremely significant, and the soluble sugar content under the treatment of 6~15 ℃ was significantly higher than that under the treatment of 20~25 ℃. ②The content of malondialdehyde (MDA) of the four forages were different under different saline alkali treatment conditions, but there were significant differences in malondialdehyde (MDA) content between high saline alkali treatment 6~15 ℃ and 20~25 ℃. ③The SOD activity of Poa pratensis, Elymus sibiricus and Elymus taundensis reached the maximum at the concentration of 5850 mg/L sodium chloride and 10 600 mg/L sodium carbonate under different salt and alkali stress, while the activity of SOD in Koeleria cristata was the highest when the concentration of sodium chloride was 8775 mg/L and the concentration of sodium carbonate was 15 900 mg/L. ④With the increase of saline alkali concentration, the root tip mortality of the four forages was higher. 6~15 ℃ could effectively reduce the damage of root cells caused by saline alkali stress. ⑤The stem length of herbage decreased with the increase of saline alkali concentration under different temperature conditions.In summary, Koeleria cristata has strong resistance to salt alkali stress in low temperature environments.