Rosmarinic acid (RA) has a wide range of biological effects, including the antioxidation and antiaging. However, the detailed mechanisms remain unclear but highly attractive. Herein, RA promoted lifespan and motoricity in a dose-dependent manner, and reduced fat store without threatening fertility in Caenorhabditis elegans. In term of antioxidant efficacy, catalase activity, glutathione peroxidas activity, reduced glutathione content, and reduced glutathione/oxidized glutathione ratio were enhanced. And malondialdehyde content was diminished significantly. Moreover, RA increased survival under acute oxidative and thermal stress, and suppressed intestinal lipofuscin accumulation. So the improvement of lifespan mediated by RA could be related with its strong antioxidant properties. Furthermore, RA was absorbed by worms. Further research in pursuit of the mechanism showed that longevity induced by RA was involved with the genes sod-3, sod-5, ctl-1, daf-16, ins-18, skn-1, and sek-1, but was independent of subcellular localization of DAF-16. These findings indicated that RA had a potential for promoting healthy lifespan.