Objective To investigate the different doses effect of metoprolol on levels of IL-βand TNF-α in peripheral blood and cardiac function in patients with dilated cardiomyopathy (DCM) and heart failure (HF). Methods A total of 110 patients with DCM and HF were divided into high dose group and low dose group according to the different doses of administrated metoprolol. The initial dose of high dose group was 11.875mg, and then the dose was doubled till the tolerance dose while the initial dose of the low dose group also was11.875mg but the dose was not doubled. After 6 months of treatment, the changes of levels of IL-βand TNF-α in peripheral blood and grade of cardiac functionin the two groups before and after treatment were observed. Results After treatment, the levels of IL-β and TNF-α in peripheral blood of the high dose group were (17.99±8.43)ng/L and (20.34±4.11)ng/L significantly lower than those of the low dose group (P<0.05). After treatment, the grade of cardiac functioning in the high dose group was significantly better than that of the low dose group (P<0.05). Conclusion High-dose metoprolol is effective in the treatment of patients with DCM and HF, and it can effectively reduce the levels of IL-βand TNF-α in peripheral blood and improve cardiac function.