Abstract: 【Objective】 To study the effects of different concentrations of 2, 4-Epibrassinolide (EBR) on the germination characteristics and key enzyme activities of tomato seeds under salt stress and determine the optimal concentration of exogenous EBR for tomato seed germination and growth in the hope of providing theoretical support for the effective application of this plant growth regulator. 【Methods】 The seeds of salt-sensitive tomato ‘M82’ and salt-tolerant tomato ‘IL-7-5-5’ were treated with 50 mmol/L NaCl, and exogenous EBR of 0.01, 0.1 and 0.5 μmol/L were added to assess tomato seed germination stage of germination rate, germination potential, morphological characteristics, and analysis of antioxidant enzymes activity and osmotic regulation substances content changes. 【Results】 Compared with salt stress treatment, the germination potential of ‘M82’ and ‘IL-7-5-5’ after exogenous EBR treatment was increased by more than 10% to 30%, and the seed vigor index was increased by more than 100 to 200. With the increase of EBR concentration, the germination rate and germination potential of the two tomato varieties showed a decreasing trend. Compared with salt stress, the seed germ length and fresh weight of ‘M82’ treated with 0.01 μmol/L EBR increased by 94.26% and 135.71%, respectively. The germ length and fresh weight of ‘IL-7-5-5’ treated with 0.1 μmol/L EBR increased by 32.48% and 14.52%, respectively, compared with salt stress. The contents of osmoregulatory substances such as soluble protein and soluble sugar were significantly increased, and the activities of MDA, SOD, CAT and POD in the sprouts were significantly increased, but there were significant differences in physiological indexes between different EBR concentrations and different tomato varieties. 【Conclusion】 In the presence of salt stress, exogenous EBR can enhance the adaptability of tomato seeds to osmotic regulation during germination, improve the efficacy of antioxidant system in vivo, reduce the accumulation of membrane lipid peroxidation products, promote the germination and growth of tomato seeds, thus enhancing the tolerance of tomato seeds to salt during germination. 0.01 μmol/L EBR treatment has the best effect on ‘M82’ and 0.1 μmol/L on ‘IL-7-5-5’ under salt stress.