Dilated cardiomyopathy (DCM) is a myocardial disorder resulting in a substantial decline in cardiac function and potentially leading to heart failure. This research combines bioinformatics analysis with empirical validation to explore the roles and mechanisms of miR-214 in DCM. Using the DEseq2 R package, a total of 125 differentially expressed circulating miRNAs (DE c-miRNAs) and 784 DE genes (DEGs) were identified. Cross-analysis between target genes of DE c-miRNAs and DEGs identified 124 common genes, and protein-protein interaction analysis of common genes identified 11 hub genes. Twelve DE c-miRNAs were further verified by quantifying their levels in the serum of DCM patients and healthy individuals. miR-214 levels were significantly decreased in serum from DCM patients, positively correlated with left ventricular ejection fraction and left ventricular fractional shortening. Further analysis showed that miR-214 directly targets and negatively regulates phosphodiesterase 5 A (PDE5A). Elevated PDE5A expression reduced cGMP levels; however, using sildenafil, a PDE5A inhibitor, reversed this effect, substantiating the regulatory mechanism of miR-214 on cGMP via PDE5A. These results provide new potential targets for the diagnosis and treatment of DCM.