Objective: To observe effects of Shenchang Injection on platelet activation and thrombosis in MCAO rats. Method: The cerebral injury model induced by ischemia/reperfusion was made in rat by MCAO. Shenchang injection was given by iv for 7 times, then CD62p、CD63 were measured by flow-cytometry. Thrombosis and clotting time were observed. Result: Shenchang injection could decrease expression of CD62p and CD63 in blood, decline thrombosis in kidney vein, delay clotting time in MCAO rats. Conclusion: Shenchang injection is effect for antiplatelet activities and postponement of thrombosis by extending blood clotting. These are likely the pharmacological basis of the injection for treating stroke.