Aim To investigate the effects and possible mechanism of metformin （Met） on anoxia/reoxygenation （A/R） injury in cultured human umbilical vein endothelial cells （HUVECs）. Methods HUVECs were cultured and anoxia /reoxygenation model was set up, then randomly divided into 5 groups:the control group, A/R group, A/R+Met（0.1 mmol/L） group, A/R +Met（0.5 mmol/L） group, A/R+Met（1.0 mmol/L） group. The apoptosis rate of HUVECs was detected by flow cytometry. The mRNA expression of nuclear factor kappa B/P65（NF-κB/P65） was quantified by real-time PCR （RT-PCR） and the supernatant concentrations of intercellular adhesion molecule（ICAM-1） and tumor necrosis factor-α（TNF-α） were detected by enzyme linked immunosorbent assay （ELISA）. Results Compared with control group, apoptosis rate of A/R group was increased（P<0.05）, the mRNA expression of NF-κB/P65 was increased significantly in A/R group, the concentrations of ICAM-1 and TNF-α were improved （P<0.05）. However, compared with A/R group, cell apoptosis rate was decreased in groups treated by metformin（P<0.05）. The mRNA expression of NF-κB/P65 was decreased significantly and the concentrations of ICAM-1 and TNF-α were reduced in metformin pretreatment groups（P<0.05）.