Aim To investigate the protective effective of casticin（CAS） against human umbilical vein endothelial cells（HUVEC） apoptosis induced by H₂O₂ oxidative stress and its possible molecular mechanism. Methods HUVEC cells were cultured in vitro. The cells which would be induced by H₂O₂ were incubated in advance for 30 minutes with ONY and various concentration of CAS. Cells viability was measured by MTT assay, and its apoptosis-inducing effect were determined by AO/EB and FCM, meanwhile western blot assay was used to measure proteins related to apoptosis.Results CAS could increase the viability of HUVEC cells induced by H₂O₂ in a dose and time-dependent manner compared with cells solo exposed to H₂O₂ （P<0.05）. The number of apoptotic cells and the apoptotic rate of HUVEC cells treated with various concentration CAS and H₂O₂ significantly decreased in a dose and time-dependent manner compared with H₂O₂ group（P<0.05）, meanwhile the expression of Cytochrome-C, Caspase-9 and Caspase-3 protein were down-regulated （P<0.05）, and protein level of Bcl-2 was activated（P<0.05）, while the expression of Bax protein showed no change in the same treatment（P>0.05）, and the ratio of Bcl-2/Bax expression level increased（P<0.05）. Conclusion CAS could prevent H₂O₂-induced HUVEC cells apoptosis which might be correlated with mitochondria-controlled apoptotic pathway.