Objective To analyze the effect of early enough metoprolol combined with thrombolysis on cardiac function and myocardial injury markers in patients with acute ST-segment elevation myocardial infarction. Methods A total of 158 patients with acute ST-segment elevation myocardial infarction admitted to Liuzhou Medical District of the 924th Hospital of the Joint Logistics Support of the Chinese People's Liberation Army from August 2018 to March 2020 were selected and divided into the control group and the research group according to the random number table method, 79 cases in each group. Patients in the control group received thrombolytic therapy, patients in the research group received early enough metoprolol combined with thrombolytic therapy, and both groups were treated for 14 days. The clinical efficacy of the two groups of patients after 14 days of treatment, the cardiac function before and after 14 days of treatment, the levels of myocardial injury markers before treatment and 3, 7 days after treatment, and the occurrence of adverse reactions during the treatment were compared. Results After 14 days of treatment, the total clinical effective rate of the research group was significantly higher than that of the control group; Compared with before treatment, the left ventricular end systolic volume (LVESV) and left ventricular end diastolic volume (LVEDV) levels of patients in the two groups significantly reduced after 14 days of treatment, and the research group was significantly lower than the control group; the left ventricular ejection fraction (LVEF) and the early diastolic flow rate (E/A) of the research group increased significantly after 14 days of treatment, and the research group was significantly higher than the control group; compared with before treatment, after 3, 7 days of treatment, the levels of troponin T (cTnT) and troponin I (cTnI) of the two groups of patients gradually decreased, and the research group was significantly lower than the control group; during the treatment period, the total incidence of adverse reactions in the research group was significantly lower than that in the control group (all P<0.05). Conclusion Early enough metoprolol combined with thrombolytic therapy can effectively reduce myocardial injury in patients with acute ST-segment elevation myocardial infarction, improve cardiac function, reduce adverse reactions, enhance the therapeutic effect, and improve the prognosis of patients.