Abstract: 【Objective】 In order to study the effects of different concentrations of brassinolide solution on seed germination and seedling growth of barley under drought stress, the optimal concentration of brassinolide solution was determined. 【Methods】 The seeds of Xinpi No.6 barley were soaked in brassinolide of different concentrations (0, 5, 25, 50, 100, 200 μg/L).The paper germination test was carried out in either distilled water (CK) or 23% polyethylene glycol solution.The germination rate, germination potential, germination index and dry and fresh weight of roots and buds were calculated.The effects of brassinolide solution with different concentrations on relative water content, electrical conductivity, contents of malondialdehyde, proline, soluble sugar and antioxidant enzyme activities in buds and roots of barley under drought stress were determined. 【Result】 Drought stress significantly inhibited barley seed germination and seedling growth. Compared with drought stress alone, 5, 25 μg/L brassinolide treatment increased the germination rate, germination potential and germination index of barley seeds by 34.23%, 65.74%, 25.80%, 45.45%, 31.82% and 47.70%, respectively. Compared with drought stress alone, 25μg/L brassinolide treatment increased the soluble sugar content in root and bud by 7.86% and 12.53%, respectively, and the free proline content in root and bud by 35.06% and 20.63%, respectively. Meanwhile, 25 μg/L brassinolide treatment increased the activities of catalase, peroxidase and superoxide dismutase in root and bud. 【Conclusion】 Suitable concentration of brassinolide could increase the content of osmomodulators and antioxidant enzyme activities in barley root and bud under drought stress, promote barley seed germination and seedling growth, and the effect of 25μg/L brassinolide treatment was the most obvious.