Objective: To ascertain the main active site of Typhae Pollen in effect of antithrombosis. Method: Screening for effect of platelet aggregation in vitro from the different extracts of Typhae Pollen(petroleum ether

ethyl acetate

butanol

water)was carried out

further study the effects of the active sites of Typhae Pollen on the collagen-adrenaline and carrageenan induced thrombosis of mice. Effect of effective parts of Typhae Pollen for the rats of thrombosis and vascular wall in vivo. Result: The ethyl acetate parts of Typhae Pollen on arachidoric acid(AA)

adenosine diphosphate(ADP)

collagen

thrombin induced rabbit platelet aggregation inhibition rates were 40.08%

33.09%

37.91%

34.71%

29.29%

compared with the water parts were 28.65%

28.33%

32.29%;while the protection rate of collagen-adrenaline induced death and paralysis in mice by the ethyl acetate parts of Typhae Pollen was 50%

carrageenan-induced mice black tail incidence was 50%;the site of ethyl acetate have significantly inhibitive effect on the thrombosis models in vivo

and significantly protective effect on vascular endothelial. Conclusion: The site of ethyl acetate is the main active site of the Typhae Pollen.