Objective To search for chemical constituents with anti-oxidative activity from seeds of Jatropha curcas. Methods DPPH radical scavenging assay was used to screen fractions or constituents with anti-oxidative activities. Active fractions were separated by varied chromatography and then identified on the basis of physiochemical properties and spectroscopic methods. Results The n-butanol layer of ethanol extract from the seeds of J. curcas showed stronger activity than other fractions and was studied further. A new compound was isolated from this active layer, and its structure was identified as jatrophasin A (3,4,4′,5′-tetrahydroxyl-3′-methoxyl-bisepoxylignan, 1). It showed stronger anti-oxidative activity compared with resveratrol. Conclusion Compound 1 is a new compound which has never been reported with strong anti-oxidative activity. Objective To search for chemical constituents with anti-oxidative activity from seeds of Jatropha curcas. Methods DPPH radical scavenging assay was used to screen fractions or constituents with anti-oxidative activities. Active fractions were separated by varied chromatography and then identified on the basis of physiochemical Results the n-butanol layer of ethanol extract from the seeds of J. curcas is extracted from the seeds of J. curcas shows stronger activity than other fractions and was studied further. A new compound was isolated from this active layer, and its structure was identified as jatrophasin A (3,4,4 ’, 5’-tetrahydroxyl-3’-methoxyl-bisepoxylignan, 1). It showed stronger anti-oxidative activity than with resveratrol. Conclusion Compound 1 is a new compound which has never been reported with strong anti- oxidative activity.