[Objective] The effects of abscisic acid on the growth, stomatal traits, and photosynthesis of Iris lactea seedlings under severe saline stress were study, so as to explore the appropriate concentration of ABA for enhancing the salt tolerance of Iris lactea seedlings under severe saline soil, and to provide a basis for the cultivation of Iris lactea in the severe saline soil. [Methods] Using Salt-tolerant germplasm ML004 and salt-sensitive germplasm ML035 seedlings of Iris lacteal, 150mmol ? L-1 NaCl solution was used to simulate the severe salt stress environment, and the effects of abscisic acid (0, 1, 2.5, 5, 10 μmol ? L-1) on the growth, stomatal traits, and photosynthesis of Iris lactea seedlings under NaCl stress were studied with no NaCl and ABA treatment as controls. [Results] Under 150mmol?L-1NaCl stress, the leaves of two Iris lactea germplasm seedlings showed salt damage symptoms of different degrees, and the salt damage symptoms of ML35 leaves were more serious than those of ML04. Spraying ABA solution increased the salt tolerance of two germplasm materials, and the effect of ABA solution on the salt tolerance of ML04 was better than ML35. Application of ABA solution could significantly increase the plant height and biomass of Iris lacteal, and the salt tolerance of Iris lactea seedlings can be improved by adjusting the stomatal morphology and spatial distribution pattern to optimize the gas exchange process, reducing the decrease of chlorophyll content and enhancing its photosynthesis. [Conclusion] The salt damage response of ML35 was more serious than that of ML04 under150mmol ? L-1NaCl salt stress. Spraying appropriate concentration of ABA could alleviate the effect of salt stress on the growth of Iris lactea seedlings. In this experiment, 2.5 μmol ? L-1 ABA solution spraying has the best effect, which is an effective method to improve the salt tolerance of Iris lacteal.