Aim To investigate the protective effects of Tongxinluo(TXL) on vascular endothelial cells injured by homocysteine and its mechanism.Methods Human umbilical vein endothelial cells(HUVEC) cultivated in vitro were divided into four groups: control group,homocysteine group,TXL group and atorvastatin treatment group.The cell proliferation ability was determined by MTT assay.Real-time reverse transcription polymerase chain reaction(RT-PCR) was performed to detect mRNA expression of superoxidase dismutase(SOD).The content of malondialdehyde(MDA) and SOD activity in HUVEC cellular supernatant were detected.Results Homocysteine significantly inhibited endothelial cell viability(P<0.05).Tongxinluo and atorvastatin significantly improved endothelial cell viability reduced by homocysteine(P<0.05).Homocysteine decreased the expression of SOD mRNA in HUVECs(P<0.01).Tongxinluo and atorvastatin increased the expression of SOD mRNA compared with homocysteine group(P<0.05).Compared with the control group,the activity of SOD in Hcy group decreased significantly(P<0.05) while the content of MDA increased dramatically.However,the activity of SOD in TXL group and atorvastatin group increased significantly compared with Hcy group(P<0.05),at the same time,the concentration of MDA in TXL group and atorvastatin decreased(P<0.05).Conclusions TXL capsule can protect the HUVECS from injury by homocysteine.And it may take an important role in the antioxidant of TXL.