To observe the effects of Danshen Decoction on the biological indexes of platelets in model rats with blood stasis due to qi deciency, and to explore the mechanism of Danshen Decoction from the dynamic changes of platelets. Methods:A total of 40 SD rats were randomly assigned to blank group, model group, high-dose Danshen Decoction group (3.6 g/kg) and low-dose Danshen Decoction group (0.9 g/kg) with 10 rats in each group after establishing the model of blood stasis due to qi deciency through injecting bleomycin saline solution into trachea at one time. On the second day after establishing model, the medicine was given through intragastric administration for 21 days. After one hour of the last administration, the rats were anesthetized with 5% chloral hydrate and blood was taken from the abdominal aorta. Blood viscosity, plasma viscosity, platelet parameters, platelet activation, adhesion, aggregation, release and related indicators of fibrinolysis were detected. Results:Compared with the model group, Danshen Decoction could significantly reduce the blood viscosity (P<0.05) and plasma viscosity (P<0.05). PDW and MPV could be reduced significantly (P<0.05). The content of cAMP could be increased significantly (P<0.05). The content of cGMP, β-TG, PF4 and PAI-1 could be reduced significantly (P<0.05). And prothrombin time (PT) and thrombin time (TT) were prolonged (P<0.05). Conclusion:Danshen Decoction could decrease whole blood viscosity to improve the blood stasis due to qi deficiency through improving the aggregation of platelet, inhibiting coagulation and the hyper-active release of platelet.