Paris Polyphylla Smith is widely used in traditional Chinese medicine. For its effective of antipyretic detoxicate, its active component is steroid saponin . The present study was designed to evaluate the antioxidative effect of extracts of Paris Polyphylla Smith (PPSE) and its capacity to protect human umbilical vein endothelial cells (HUVECs) against oxidative damage induced by oxidized low density lipoprotein (ox-LDL). Cytotoxicity was determined by MTT assay. Flow cytometer (FCM) demonstrated that the increased apoptosis induced by oxidized low density were inhibited, and the blocked transition of cells from static phase (G0/G1) to DNA synthesis (S) were restored by PPSE, these effect were all in a dose-dependent manner. The actions by PPSE to reduce apoptosis may help protect endothelial function and inhibit atherogenesis, while the novel actions to mitigates oxidative stress may weaken the ability of endothelial injury. Further studies are needed to identify the chemical compounds responsible in order to develop its clinical application.