OBJECTIVE： To study the inhibitory effects of berberine on EA.hy926 human umbilical vein endothelial cells （EA.hy926 cells） injury induced by particulates with no more than 2.5 μm air aerodynamic diameter in atmospheric （PM2.5）， and its p38 mitogen-activated protein kinase （MAPK） signal pathway mechanism. METHODS： PM2.5 samples were collected and hatched EA.hy926 cells with concentrations of 0 （blank control）， 20， 200 and 400 mg/L for 24 h. The survival rate and apoptosis rate of cells， contents of IL-6， TNF-α and MDA， activities of SOD and LDH， protein levels of p-p38 MAPK， Bcl-2 and Bcl-2 associated X protein （Bax） were detected. The above indexes of EA.hy926 cells in blank control group， PM2.5 group （200 mg/L PM2.5）， p38 MAPK pathway-specific blocker SB203580 group （20 μmol/L SB203580+200 mg/L PM2.5）， berberine low-， medium- and high-concentrations groups （5，10，20 μmol/L berberine+200 mg/L PM2.5） were also determined. RESULTS： Compared with blank control， survival rate of cells， SOD activity and Bcl protein decreased after 200， 400 mg/L PM2.5 hatched； apoptosis rate of cells， contents of IL-6， TNF-α and MDA， LDH activity， protein levels of p-p38 MAPK and Bax increased （P＜0.05）， in concentration-dependent manner. Compared with PM2.5 group， survival rate of cells， SOD activity and Bcl-2 protein increased in berberine medium-， high-concentrations groups and SB203580 group； apoptosis rate of cells， contents of IL-6， TNF-α and MDA， LDH activity， protein levels of p-p38 MAPK and Bax decreased （P＜0.05）. CONCLUSIONS： Berberine attenuates PM2.5-induced EA.hy926 cells injury via the inhibition of p38 MAPK pathway.