Aim To investigate the regulatory role of miR-146a in the senescence of human umbilical vein endothelial cells and its mechanism. Methods The replication aging model of human umbilical vein endothelial ECV-304 cells was established. Senescence-associated β-galactosidase (SA-β-gal) method was used to detect the ratio of senescent cells in different generations cells (P2, P6, P9, P12, P15 generation); real time quantitative PCR method was used to detect the level of miR-146a in different generations cells (P2, P6, P9, P12, P15 generation); Target gene prediction software was used to predict the target gene of miR-146a. The cells in P12 generation were transfected with Pre-miR146a, Pre-miR146a control, Anti-miR146a , and Anti-miR146a control; SA-β-gal method was used to detect the ratio of senescent cells; Western blot was used to detect the protein expression of NADPH oxidase 4(NOX4). Results The ratio of senescent cells in P6, P9, P12 and P15 generations was significantly higher than cells in P2 generation (P<0.05). And the expression of miR-146a in P6, P9, P12 and P15 generations was significantly lower than cells in P2 generation (P<0.05). Predicting the target gene of miR-146a was NOX4. After transfection, the ratio of senescent cells in Pre-miR146a group was significantly lower than control group (P<0.05), but it was significantly higher in Anti-miR146a group (P<0.05). The expression of NOX4 protein in Pre-miR146a group was significantly lower than control group (P<0.05), but it was significantly higher in Anti-miR146a group than control group (P<0.05). Conclusion The expression of miR-146a decreased in the aging human umbilical vein endothelial ECV-304 cells, the up-regulation of miR-146a expression can inhibit ECV-304 senescence, and its mechanism is related to the regulation of NOX expression.