OBJECTIVE：To obeserve the effect of RNSP on blood rheology in increased blood viscosity rat and analysis its machanism that is related to cerebral vascular.METHOD:The animal model of acute blood stagnation was formed quickly in rats by injected Adrenaline and cold water stimulation,the parameter of blood rheology were measured.RESULTS:RNSP 0.5g/kg and 1g/kg markedly decreased whole blood viscosity(ηb) and whole blood reduced viscosity(ηr) at shear rates of 10s-1,50s-1 and 120s-1,specially at low shear rate,deduced the aggregation inder of RBC(AI) and hemotocrit(Hct).At the same time,no effects on bleeding time and clotting time were observed.The effect of RNSP 1g/kg is similar to that of injectio salvia miltiorrhiza(SM).CONCLUSION:RNSP had the inhibition effect on the aggregate and coagulate function of Red blood cells,and would decrease the blood viscosities.It promoted the blood circulation to remove blood stasis,but had no effect on bleeding time and clotting,in normal animals.