To explore the therapeutic effect and safety of Metoprolol Succinate Sustained-release Tablets combined with Wenxin granules in treating ventricular arrhythmia after myocardial infarction. Methods: Sixty five patients with ventricular arrhythmia after myocardial infarction were randomly divided into observation group (n=34) and control group (n=31). Patients in the observation group were given Metoprolol Succinate Sustained-release Tablets combined with Wenxin granules, and patients in the control group were treated with Metoprolol Succinate Sustained-release Tablets. Dynamic electrocardiogram, symptom improvement, and QT dispersion changes were compared before and after treatment. Also, adverse reactions of the drugs were observed. Results: After 4 weeks of treatment, symptoms in both groups were improved; the occurrence of ventricular premature beat or ventricular tachycardia were less in observation group compared with the control group; there were decrease of QT dispersion in both groups, and the observation group had more obvious reduction. Conclusion: Metoprolol Succinate Sustained-release Tablets combined with Wenxin granules shows satisfactory therapeutic effect in treating ventricular arrhythmia after myocardial infarction, and it could effectively prevent malignant arrhythmia, which is worth generalizing.