The aim of this study is to assess the potential protective effect of oleanolic acid (OA) against ox-LDL induced damage in human umbilical vascular endothelial cells (HUVECs) and investigate potential mechanism of action including antioxidative effects and inhibition of mitochondria apoptosis pathway. Cell counting kit 8 was used to evaluate the viability of HUVECs. 2', 7'-DCFH-DA staining and flow cytometry was used to assess the levels of intracellular reactive oxygen species in HUVECs. The protein expression levels of uncoupling protein 2, cytochrome C, and apoptosis induction factors were measured by western blotting. The results indicated that OA treatment alleviated ox-LDL induced cytotoxicity in HUVECs and ameliorated the reactive oxygen species levels. Western blotting results demonstrated that OA treatment increased the expression level of uncoupling protein 2 and decreased the release of cytochrome C and apoptosis induction factors from mitochondria to cytoplasm, suggesting inhibition of mitochondria apoptosis pathway. In conclusion, OA could protect HUVECs from ox-LDL-induced cytotoxicity; its antioxidant property and inhibition of mitochondria apoptosis are likely crucial contributors.