Homocysteine plays a key role in endothelial cell senescence associated with atherosclerosis-based cardiovascular diseases. Selaginellin, a component extracted from Selaginella pulvinata (Hook. et Grev.) Maximo, was assessed for its ability to protect human umbilical vein endothelial cells against homocysteine-induced senescence. The endothelial cells were pretreated with various concentrations (10− 7, 3× 10− 7, or 10− 6 M) of selaginellin for 1 hour before exposure to homocysteine. Selaginellin was shown to protect endothelial cells against homocysteine-induced senescence, as determined by senescence-associated β-galactosidase activity, telomerase activity, and cell cycle distribution. In addition, the increase in levels of intracellular reactive oxygen species and downregulation of SIRT1 gene expression induced by homocysteine were significantly reversed by selaginellin. Our study suggests that selaginellin has a protective effect against homocysteine-induced senescence through mechanisms related to antioxidation via scavenging reactive oxygen species and upregulating the expression of SIRT1 gene.