Salinity considered one of abiotic stress affected to crop productivity. The present investigation aimed to give insights about the effect of NaCl saline on two cultivars sunflower plants (Helianthus annuus. L) and determine the usefulness of increasing relative salt tolerance by auxin treatment. Different responses of two sunflower cultivars Sakha 53 and China and differently susceptible to salinity stress levels by NaCl treatment in hydroponic culture experiment were investigated. The cultivar more tolerant (Sakha 53) showed less reduction in height , fresh and dry weight of the different plant organs, membrane stability, plastid pigments contents and more expression of antioxidant enzymes under high salinity level (175 mM NaCl) compared with China cultivar. Also the growth parameters were significantly increased due to IAA treatments. The physiological mechanisms of tolerance to salinity are descussed at the cellular, organ was studied. The use of plant hormones in two sunflowers under NaCl stress, improved plants salt tolerance through an improvement of relative water content, membrane stability, enhancement of chlorophyll and carotenoids biosynthesis, some antioxidant enzymes, which reflect an increase the most growth parameters of sunflower. Thus, our tested phytohormones prevent the harmful effects of NaCl in two sunflowers.