Objective: To investigate the effects of external counter pulsation (ECP) on cardiac function, platelet activation, and endothelial dependent vasomotor function in patients with unstable angina (UA). Methods: A total of 106 patients with UA admitted to Qinhuangdao Workers’ Hospital from July 2018 to May 2021 were selected and randomly divided into 2 groups, with 53 cases in each group. The control group was treated with conventional western medicine, and the observation group was treated with ECP on the basis of the control group. The clinical efficacy, cardiac function, platelet activation, endothelial dependent vasomotor function, and safety of the 2 groups were compared. Results: The total effective rates of the observation group and the control group were 94.34% and 81.13%, respectively, with significant difference (P<0.05). After the treatment, the left ventricular ejection fraction (LVEF), stroke volume (SV), and cardiac output (CO) in the observation group were significantly higher than those in the control group (all P<0.05), and left ventricular end-diastolic diameter (LVEDD) was significantly lower than that in the control group (P<0.05). After the treatment, the expression levels of platelet microparticles (PMPs) surface membrane glycoprotein (CD62p, CD63), glycopropean complex of activated platelets (PAC-1) and lysophosphatidic acid (LPA), and the content of serum endothelin-1 (ET-1) in the observation group were significantly lower than those in the control group (all P<0.05), and the content of serum nitric oxide (NO) was significantly higher than that in the control group (P<0.05). During the treatment, no serious adverse reactions occurred in the 2 groups. Conclusion: ECP adjuvant treatment of UA can improve cardiac function of patients, and its mechanism may be related to the improvement of platelet activation and endothelial dependent vasomotor function.