Objective: To investigate the effect of metoprolol on cardiac function and prognosis in patients with dilated cardiomyopathy. Methods: 100 patients with dilated cardiomyopathy treated in our hospital from January 2018 to December 2019 were randomly divided into control group (n = 50) and observation group (n = 50). The control group was treated with conventional methods, and the observation group was treated with conventional methods and metoprolol for 6 months. The cardiac function [left ventricular ejection fraction (LVEF), stroke volume (SV), cardiac output (CO)] and prognosis [Glasgow Outcome Scale (GOS) score] of the two groups before and at the end of 6 months of intervention were compared, and the incidence of adverse reactions of the two groups were compared. Results: After 6 months of treatment, the levels of LVEF, SV and CO in the two groups were higher than before treatment, and the comparison level between the observation group and the control group was higher, the difference was statistically significant (P < 0.05);After 6 months of treatment, the GOS score of the observation group was higher than that of the control group, and the difference was statistically significant (P < 0.05);There was no significant difference in the total incidence of adverse reactions between the two groups (P > 0.05). Conclusion: Metoprolol can improve the cardiac function and prognosis of patients with dilated cardiomyopathy, without increasing the incidence of adverse reactions.