Background: The acute blockage in coronary arteries further causes acute coronary syndrome (ACS). There are 2 main factors implicated in the activation and aggregation of platelets. However, this present study aimed to investigate the effect of salvianolic acid A (SAA) on the platelets in patients with ACS and explore its potential mechanism of action. Methods: The impact of SAA on platelets under different stimulation conditions was studied using flow cytometry and platelet aggregation detection techniques. Results: The results demonstrated that in 40 ACS patients, ex vivo treatment of platelets with SAA (0.1 mg/ml) significantly reduced aggregation and activation. Intriguingly, we found no significant difference between the 3 types of ACS patients in the antiplatelet effect of SAA. Moreover, the results indicated that C-reactive protein, alanine aminotransferase, C-reactive protein-to-albumin ratio, total cholesterol, and low-density lipoprotein levels were negatively correlated with the anti-platelet effect of SAA in ACS patients and that a history of smoking may reduce the anti-platelet effect of SAA in the same group. Conclusion: In summary, the above findings of this study highlight the therapeutic potential of SAA against platelets in patients with ACS, providing new insights into clinical treatment and experimental research.