Objective:To investigate the effect and safety of Guanxinning Tablet(冠心宁片,GXN) for the treatment of stable angina pectoris patients with Xin (Heart)-blood stagnation syndrome (XBSS).Methods:One hundred and sixty stable angina pectoris patients with XBSS were randomly assigned to receive GXN (80 cases)or placebo (80 cases,Guanxinning simulation tablets,mainly composed of lactose),4 tablets (0.38 g/tablet),thrice daily for 12 weeks.After treatment,an exercise stress test (treadmill protocol),Chinese medicine (CM)syndrome score,electrocardiogram (ECG),and nitroglycerin withdrawal rate were evaluated and compared in the patients between the two groups.Meanwhile,adverse events (AEs) were evaluated during the whole clinical trial.Results:Compared with the control group,the time extension of exercise duration in the GXN group increased 29.28 ± 17.67 s after treatment (P＞0.05);moreover,the change of exercise duration in the GXN group increased 63.10± 96.96 s in subgroup analysis (P＜0.05).The effective rates of angina pectoris,CM syndrome and ECG as well as nitroglycerin withdrawal rate were 81.33％,90.67％,45.76％,and 70.73％,respectively in the GXN group,which were all significantly higher than those in the control group (40.58％,75.36％,26.92％,28.21％,respectively,P＜0.05).Conclusion:GXN was a safe and effective treatment for stable angina pectoris patients with XBSS at a dose of 4 tablets,thrice daily.