Abstract: 【Objective】In vitro antioxidant activity of water extract from highland barley sprout during germination was investigated.【Method】Taking clearance rate of hydroxyl free radical and reduction capacity of metal ions as the evaluation indicators, the change rules of in vitro antioxidant activity of highland barley and contents of four functional ingredients〔flavonoids, total phenols, β-glucan, γ-aminobutyric acid (GABA)〕in the process of soaking and germination were studied, and correlation analysis were conducted. And the antioxidant activity of highland barley sprout, malt, millet sprout and rice sprout was compared.【Result】The results showed that, with the extension of soaking time and germination time, the antioxidant activity of highland barley sprout showed the trend of rising first and then falling, and it reached the peak under soaking treatment for 6 h (clearance rate of hydroxyl free radical was 64.88% and reduction capacityof metal ions was 0.910), while the value reached the peak under germination treatment for 8 h (clearance rate of hydroxyl free radical was 71.23% and reduction capacity of metal ions was 1.337). The correlation analysis showed that there was a significant correlation between the GABA content and the antioxidant activity during highland barley soaking. The antioxidant activity of the four kinds of grain(highland barley sprout, malt, millet sprout and rice sprout) bud powders increased with the increase of sample concentration. At the same concentration, the hydroxyl radical scavenging rate of malt was the highest, and the metal ion reduction capacity of highland barley sprout was the lowest. 【Conclusion】 Germination treatment can improve the antioxidant activity of highland barley. It can be used as an effective modification method to develop functional products of highland barley and promote the deep processing and utilization of highland barley resources.