Abstract：Objective：To observe the clinical effect of Guanxinning tablets for unstable angina pectoris in coronary heart disease and its effect on ventricular repolarization. Methods：A total of 63 cases of patients with unstable angina pectoris in coronary heart disease were divided into the control group and the experiment group according to the method of random sampling， with 31 and 32 cases in each group respectively. The control group was treated with routine western medicine，and the experiment group was additionally treated with Guanxinning tablets based on the treatment of the control group. Before and after treatment，the Chinese medicine syndrome scores，QT interval，Tp- e interval and Tp- e/QT ratio in the two groups were compared. The clinical effects and safety in the two groups were evaluated. Results： One case in the control group and two cases in the experiment group dropped out. In the end，a total of 60 cases were included in the clinical study. After treatment，the total effective rate was 93.33% in the experiment group，higher than that of 76.67% in the control group(P＜0.05). After treatment，the Chinese medicine syndrome scores ， QT interval ， Tp-e interval and Tp-e/QT ratio in the two groups were decreased when compared with those before treatment(P＜0.05)， and the improvement of the above indexes in the experiment group was better than that in the control group(P＜0.05). Before and after treatment， there was no significant difference being found in the comparison of levels of creatinine， alanine aminotransferase and oxaloacetic transaminase between the two groups(P＞0.05). Conclusion： Guanxinning tablets combined with western medicine has a definite curative effect in treating unstable angina pectoris in coronary heart disease，which can effectively relieve symptoms of angina pectoris and improve ventricular repolarization with high safety.