Human washed platelets and cultured confluent human umbilical vein endothelial cells were incubated with 764-3 which is exracted from Salvia miltiorrhiza Bge(SM) in China, at concentrations of 12.5,25,50,100,125,250 and 500 mg.L-1.It was found that 764-3 inhibit the espression of α-granular membrane protein 140 and platelet membrane glucoprotein Ⅱ_b/Ⅲ_a complex on platelet surface,and it increased the expression and activity of thrombomodulin on the surface of the endothelial cells. Our data provided new evidences for the antithrombotic effect of 764-3.