In this paper, three compounds were isolated and identified from the leaves of Salix matsudana. They are apigenin-7-0-beta-D-glucopyranside(I), luteolin-7-0-beta-D-glucopyranside(II), compound III. Compound I and II are isolated firstly from Salix spp., compound III is found firstly in the world. Furthermore, study on effect of arachidonic acid metabolisin in rat platelets by them with radio-chromatography found that they can significantly inhibit the production of 12-HETE(12-hydroxy-5,8, 10,14-eicosatetraenoic acid), which can induce allergy and arteriosclerosis. The production of apigenin-7-0-beta-D-glucopyranside being hydrolyzed was apigenin, it can inhibit TXB2(thromoxane B2) which can induce platelet aggregation.