Aim To investigate whether bone marrow mesenchymal stem cells （MSC） reduce the apoptosis of human umbilical vein endothelial cells （HUVEC） induced by oxidized low density lipoprotein （ox-LDL）,and related mechanisms. Methods The HUVEC were divided into three groups: HUVEC were cultured in normol medium HUVEC were cultured with 100 mg/L ox-LDL for 24 h and HUVEC were cocultured with MSC with 100 mg/L ox-LDL for 24 h. Then cell apoptosis of different groups were mesured by flow cytometry. The content of VEGF,as well as TNF-α,in supernatant medium were determined by ELISA,and Real-time PCR was used to detect Bcl-2 and Bax mRNA expression. Results After 24 h stimulated by ox-LDL,the HUVEC apoptosis rate was increased,and the content of VEGF,TNF-α were significantly increased,while Bcl-2 mRNA expression was downregulated and Bax mRNA upregulated. The MSC cocultured with HUVEC could increase the VEGF levels,reduce TNF-α levels,as well as increase Bcl-2 mRNA expression but reduce the expression of Bax mRNA,HUVEC apoptosis was significantly decreased. Conclusions MSC can attenuate HUVEC apoptosis induced by ox-LDL,possibly through the increase of VEGF,reduction of TNF-α,and upregulation of Bcl-2 mRNA and downregulation of Bax mRNA,which provides a theoretical basis for MSC as a treatment for endothelial injury disease such as atherosclerosis.