Abstract: 【Objective】 To investigate the effects of exogenous butyric acid on the growth period, agronomic traits, yield and quality of barley under different drought stress in the hope of providing a theoretical basis for the study of barley drought resistance. 【Methods】 Xinpi 4 was used as experimental material.The effects of exogenous butyric acid on the growth period, agronomic traits, yield and quality of barley under drought stress were compared and analyzed by water treatment and γ-aminobutyric acid treatment. 【Results】 Exogenous butyric acid seed dressing had no effect on seedling emergence stage and heading stage, but spraying it at flowering stage had a certain effect on maturity stage, and slightly delayed the maturity stage.Under drought stress, seedling emergence stage was not affected, heading stage and maturity stage were advanced.Exogenous butyric acid had no significant difference in basic seedling under drought stress, but had significant difference in maximum total stem number, panicle number and tiller percentage.Plant height, panicle length, panicle grain number and 1000-grain weight increased with exogenous butyric acid treatment.Exogenous butyric acid treatment could improve the yield of barley under drought stress, and the three application techniques of seed dressing, spraying at flowering stage and spraying at seed dressing and flowering stage could reduce the drought loss of barley by 7.0%, 6.3% and 18.3%, respectively.Exogenous butyric acid could increase amylose starch ratio, but has no significant effect on protein content. 【Conclusion】 Exogenous butyric acid seed dressing can increase the total number of stem and panicle of barley, while spraying can increase the 1000-grain weight of barley.The yield, drought resistance and amylose ratio of barley under drought stress are improved by seed dressing and spraying at flowering stage.