Abstract: This study was designed to compare the antithrombotic effects of salvianolic acid A and aspirin. The anti-platelet aggregation and anticoagulant effects of salvianolic acid A and aspirin in vitro and in vivo were investigated in normal rats. The anti-cerebral ischemia and anti-platelet aggregation effects of salvianolic acid A and aspirin were also investigated in rats with thrombotic cerebral ischemia. All animal care and experimental procedures were reviewed and approved by the Animal Ethics Committee of Chinese Academy of Medical Sciences. The results of antiplatelet aggregation in vitro and in vivo showed that salvianolic acid A could mildly inhibit adenosine diphosphate (ADP), arachidonic acid (AA) and thrombin (THR)-induced antiplatelet aggregation in a dose-dependent manner, while aspirin played a strong inhibitory effect on AA-induced platelet aggregation in vivo. The effects of salvianolic acid A and aspirin on the coagulation system were similar. At the same time, the results of maximum platelet aggregation rate (MAR) in the rat cerebral ischemia modelMAR_ADP=(41.67±4.55)%, MAR_AA=(53.22±2.83)%, MAR_THR=(73.33±5.04)% indicated that salvianolic acid A could mildly inhibit ADP and AA-induced antiplatelet aggregationMAR_ADP=(26.13±4.60)%, MAR_AA=(35.53±13.73)%, P<0.01, while aspirin played a strong inhibitory effect on AA-induced platelet aggregationMAR_AA=(8.13±2.99)%. Salvianolic acid A (10 mg·kg^-1) significantly improved the neurological function, cerebral infarction volume(10.77±7.80)% and brain edema(79.72±0.83)% compared with the model group(43.50±12.69)%, (82.25±0.89)% (P<0.01), while the effect of aspirin (100 mg·kg^-1) was not obvious. The above results suggest that compared with aspirin, salvianolic acid A provided a mild inhibitory effect on platelet aggregation and protected against cerebral ischemia induced by thrombus. Therefore, salvianolic acid A has a good application prospect in the prevention and treatment of thrombotic diseases.