Objective    To investigate the effects of N-nitro-L-arginine methyl ester （L-NAME）as a nitric oxide synthase inhibitor on the expression of eNOS and VE-cadherin in human umbilical vein endothelial cell (HUVEC).   Methods   Subculturing HUVECs were identified with specific antibody to CD31. 3 groups (control group, 0.1mmol/L L-NAME group, 1.0 mmol/L L-NAME group) were designed to carry out in this study. The effects of L-NAME on HUVEC activity was assessed with MTT assay. Expression of eNOS and Ve-cadherin protein in HUVEV of all group were detected with immunocytochemistry staining or Western blot. Results   More than 95% subculturing HUVECs were CD31+ cell. MTT assay showed a L-NAME dose-dependent reduction in HUVEC activity when L-NAME was added into medium. The immunofluorescence intensity of eNOS positive staining in 0.1 mmol/L L-NAME group and 1.0mmol/L L-NAME group were obviously decreased as compared with control group（P<0.01）. The immunofluorescence intensity and the relative expression of VE-cadherin positive staining in 0.1mmol/L L-NAME group and 1.0 mmol/L L-NAME group were obviously increased as compared with control group（P<0.01）.   Conclusions  L-NAME suppresses the expression of eNOS and cell activity, but improves the expression of VE-cadherin in HUVEC.