Abstract: The Japanese snake root(Ophiorhoza japonica Bl.) was used as the raw material, soaked in anhydrous ethanol and then extracted by organic solvents with different polarities. Based on the preliminary analysis of the antioxidant activities of different extraction parts, the chemical components of each extraction parts were isolated and purified using chromatographic separation techniques including silica gel and Sephadex LH-20 column chromatography, in order to disclose the antioxidant active substances basis of the this plant. The results showed that each extraction part of petroleum ether, ethyl acetate and chloroform from O. japonica Bl. exhibited antioxidant potencies. Among them, the chloroform extraction displayed best activities, with scavenging rates against 1, 1-diphenyl-2-picrylhydrazyl free radical(DPPH·) and 2, 2′-azinobis-3-ethylbenzthiazoline-6-sulfonic acid free radical(·ABTS⁺) of 86% and 89%, respectively. Subsequently, ten compounds were separated and identified as(E)-3-((9H-pyrido3, 4-b indol-1-yl) methyl)-2-ethylidenepentane-1, 5-diol(1, deppeaninol), 6-hydroxyharman(2), harman base(3), p-hydroxy benzaldehyde(4), scopoletin(5), 3-oxo-α-ionol(6), loliolide(7), β-sitosterol(8), 3-epi-pomolic acid(9) and 1-monoolein(10). Among them, compounds 1, 4, 6, 7, 9 and 10 were identified from the genus of Ophiorrhiza for the first time. The results of free radical scavenging assays showed that compound 2 exhibited significant antioxidant activity with the half inhibitory concentration(IC₅₀) of DPPH· and ·ABTS⁺ were 0.209 and 0.212 mmol/L, respectively.