To reveal the physiological response of daylily plant to salinity,the experiment studied the change of growth and some physiological indicators of Datong daylily under the mixed salt stress of isoconcentration of NaCl and Ca(NO₃)₂ in sand culture by irrigating the nurtrient solution.The results showed that the morphological indexes,biomass and leaf water content of daylily decreased obviously,root water content was relatively stable with the increase of salt concentration(0—250 mmol/L),and some plants were dead under 200 and 250 mmol/L mixed salt stress on the 20th day after treatment.With the increase of salt concentration, the plasma membrane permeability and proline content increased significantly during treatment, the AsA content decreased gradually on the 5th day of treatment, and showed the change of increase-decrease after 10 d.The content of soluble sugar decreased gradually on the 5th day of treatment,decreased significantly after 10 d,while the content of soluble protein was almost unchanged.The research illustrated that the membrane lipid peroxidation aggravated, and the water content in the aerial part decreased under mixed salt stress,which inhibited the growth of daylily plant.But the salt tolerance of daylily plant was strong,and the damage caused by salt stress could be partly alleviated by promoting the synthesis of antioxidants and organic osmolytes.Daylily could still grow normally under 150 mmol/L mixed salt stress, and the plant life was threatened beyond this concentration,and 200 mmol/L was the lethal salt concentration for daylily.