Abstract: The essential oils of different parts (flowers, root, leaves) of Amomum tsaoko were extracted by steam distillation. The components of essential oils were analyzed by GC-MS. Through computer mass spectrometry and manual analysis, the compounds were characterized by retention index method, and the relative contents were calculated by peak area normalization method, and the antioxidant capacity of different parts of essential oils in vitro was compared. The results showed that the extraction rate of essential oil reached 0.79%. 26, 25 and 34 compounds, accounting for 98.87%, 99.75% and 97.56% were identified from the essential oils of grass fruit flowers, roots and leaves. There were 19 compounds in the three parts, which accounted for 90.7%, 67.05% and 80.79% of the total number of essential oils in each part. The essential oils of different parts of grass fruit had certain antioxidant capacity, among which the highest scavenging capacity of grass fruit root essential oil on DPPH free radical was (11.79±0.73) μmol Trolox/g. The highest scavenging ability of the essential oil on ABTS⁺·was (112.96±1.22) μmol Trolox/g. The maximum reduction of Fe³⁺ by essential oils of stems and leaves was (77.91±0.38) μmol Trolox/g.