For the purpose of preventative treatment for oxidative stress-mediated diseases and anti-aging, a high-antioxidant compound was isolated from the roots of Incarvillea younghusbandii Sprague for the first time through silica gel column chromatography, reverse-phase C18 column chromatography and reverse-phase semi-preparative HPLC using a bioassay-guided fractionation technique, and was identified as acteoside by ESI-MS, GC-MS, 1D- and 2D-NMR. Feeding Drosophila melanogaster with acteoside, significant life span prolonging effect were achieved at the dosage range from 0.64 to 2.56 mg mL(-1). Positive relationships existed between the dosage and the life span prolonging effect. Otherwise, acteoside possess better life span prolonging effect in females than in males.