Purpose To study on the antithrombotic effect of polysaccharide of Auricularia auriculajudae.Methods The method of hot water extraction for extracting polysaccharide from Auricularia auriculajudae was used. The antithrombotic effect was studied by animal experiments.The length and the weight of arterial thrombosis were determined. Characteristic thrombus formation time (CTFT), and thrombus formation time (TFT),the rate of platelet adhesion and the blood viscosity were determined also.Results As compared with the normal saline group,polysaccharide of Auricularia auriculajudae(ig) remarkedly prolonged CTFT and TFT.The length of thrombus was shortened. Thrombus wet weight, thrombus dry weight,and blood viscosity were decreased, yet had no significant influence on the rate of platelet adhesion.Conclusion Polysaccharides of Auricularia auriculajudae can significantly inhitit the formation of thrombus.