Aim To investigate the effects of oxidized high density lipoprotein(ox-HDL) on apoptosis and intracellular free calcium concentration (i) of human umbilical endothelial vein cells and to infur its possible mechanism of this ECV304 injure. Methods Ox-HDL was incubated with Cu 2+, and different concentrations of ox-HDL was incubated with endothelim cells. PI staining test was conducted to analyze apoptosis index, and i was determined by fluo-3/AM, the injury of cells was observed by scanning electronic microscopy(SEM). Results High-concentration ox-HDL can induce the injury and apoptosis of ECV304 cells; the level of intracellular free calcium concentration also increase with the increasing concentration of the ox-HDL. In detail, with the prolongation of incubation period, the endothelial injury,apoptosis and intracellular calcium also increased. Conclusions High_concentration ox-HDL showed synergetically injurious effects on endothelial cells, which aggravated the apoptosis and intracellular free calcium concentration of ECV304 cells. This may at least partly attribute to the hypothesis that the increase of intracellular calcium may mediate the apopotosis of the endothelial cells ,which plays a role in the development of atherosclerosis.