The bulbs of Lilium ‘Red Palace’ were used to study the physiological characteristics of lily in response to salt stress and comprehensively evaluate the salt tolerance of lily.Different concentrations of NaCl including 0 mmol/L，50 mmol/L，100 mmol/L，150 mmol/L，and 200 mmol/L were set up.The effects of salt stress on photosynthetic pigments，photosynthetic parameters，osmoregulatory substances and anatomical structure of leaf were analyzed，correlation analysis and principal component analysis on related indexes were conducted.The results showed that the content of chlorophyll a （Chl a） and chlorophyll b （Chl b） in lily leaves decreased significantly with the prolongation of stress time，while the content of free proline （Pro） and soluble protein continued to increase.The content of malondialdehyde （MDA） had a trend of first increasing and then decreasing under the treatment of 50-150 mmol/L NaCl，and an increasing trend under the treatment of 200 mmol/L NaCl.When subjected to stress for 30 days，the net photosynthetic rate （P_n） and transpiration rate （T_r） of the leaves were inhibited，stomatal conductance （G_s） decreased with the increase of NaCl concentration，intercellular CO₂ concentration （C_i） had a trend of first decreasing and then increasing，while water use efficiency （WUE） had a trend of first increasing and then decreasing.The continuous increase in salt concentration inhibited the growth of lily leaves and buds.The anatomical structure indexes of leaves had a decreasing trend in leaf thickness （LT），upper epidermal thickness （UE），lower epidermal thickness （LE），and palisade tissue thickness （PT），except for an increase in sponge tissue thickness.The spongy ratio （SR） increased，while the palisade tissue thickness/spongy tissue thickness ratio （P/S） decreased.The results of principal component analysis showed that there was a significant positive correlation between P_n and T_r，Chl b，LT，and a significant negative correlation with Pro.It is indicated that the concentration of 100 mmol/L is the salt tolerance threshold for lily，and P_n，T_r，G_s，Chl b，LT，and Pro can be used as effective indexes to evaluate the salt tolerance of lily.Lily mainly alleviate salt damage by reducing T_r，G_s，C_i and accumulating osmoregulatory substances under low salt stress.The growth of lily is hindered，and the stress resistance of leaf anatomical structures is weakened under high salt stress.Non-stomatal factors are the main limiting factors for P_n.