Abstract： Objective To investigate the antagonism of calcium dobesilate in vascular endothelial cells (VEC) injury by Nor cantharidin and to determine effective concentration of calcium dobesilate in the antagonism.Methods Human Umbilical Vein Endothelial Cells (HUVEC) were cultured in vitro and randomly divided into three groups:Control group,Toxic group,and Intervention groups.The 3-( 4,5-dimethylthiazol-2-yl) -2,5-dipheny-ltetrazolium bromide (MTT) assay and Trypan Blue staining were applied to detect the living cells percentage.Results Four methyl azo thiazole blue (MTT) assay showed the living cells percentage of the Intervention groups arised from (48.3 ± 2.0) ％ to ( 69.4 ± 3.8 ) ％,while the living cells percentage of intervention group with 80 mmol/L calcium dobesilate was obviously higher than that of the toxic group.Conclusions Nor cantharidin can effectively inhibit the proliferation of VEC and lower the living cells percentage of the cells.While the calcium dobesilate with a concentration of 80 mmol/L shows an antagonism of the toxicity of Nor cantharidin as well as an effect of protecting the VEC.