Aim To investigate the role and mechanism of TSG on the apoptosis of human umbilical vein endothelial cells(HUVEC) induced by H2O2. Methods HUVEC were treated with TSG(0.1,1,10 and 100 μmol/L) for 24 hours then exposed to H2O2(100,200,300,400 and 500 μmol/L) for 24 hours,the optimal concentration of H2O2 and TSG were dedected by MTT and Flow Cytometry. Morphology of apoptosis and the protective effect of TSG on HUVEC induced by H2O2 were observed by Hoechst33258 staining.The mRNA and protein expression of Caspase-3 were detected by RT-PCR and Western blot analysis respectively. Results According to the MTT and Flow Cytometry,the optimal concentration for H2O2 to establish apoptosis model and for TSG to protect HUVEC induced by H2O2 were 300 μmol/L and 10 μmol/L respectively.Compared with the control group,the group of 300 μmol/L H2O2 inhibited the cell proliferation,increased the number of apoptotic cells and the expression of Caspase-3 significantly.Compared with H2O2 group,10 μmol/L of TSG improved the rate of cell proliferation,inhibited cell apoptosis,and decreased expression of the caspase-3 significantly(P<0.05). Conclusion TSG could inhibit H2O2-induced apoptosis of HUVEC,and its mechanism was associated with the inhibition of Caspase-3 expression.