Objective To investigate the correlation between serum microRNA-210 （miR-210）， tumor necrosis factor-stimulated gene 6 （TSG-6）， and complement C1q tumor necrosis factor-related protein 3 （CTRP3） and their association with myocardial fibrosis and prognosis in patients with dilated cardiomyopathy （DCM）. Methods A total of 117 patients with DCM admitted to Taizhou People's Hospital between March and August 2024 were enrolled in the DCM group. Based on cardiac magnetic resonance imaging findings， these patients were further classified into a myocardial fibrosis group （n = 96） and a non-fibrosis group （n = 21）. Additionally， according to the occurrence of acute heart failure during one-year follow-up， they were categorized into a heart failure group （n = 47） and a non-heart failure group （n = 70）. Concurrently， 58 age- and sex-matched healthy volunteers were recruited as the control group. Serum levels of miR-210， TSG-6， CTRP3， N-terminal propeptide of type Ⅲ procollagen （PⅢNP）， left ventricular ejection fraction （LVEF）， and N-terminal pro-B-type natriuretic peptide （NT-proBNP） were measured and compared across all groups. Results The DCM group exhibited significantly higher serum levels of miR-210， TSG-6， PⅢNP， and NT-proBNP， lower CTRP3 levels， and reduced LVEF compared to the healthy controls （P < 0.05）. Similarly， the fibrosis group showed elevated serum levels of miR-210， TSG-6， PⅢNP， and NT-proBNP， decreased CTRP3 levels， and impaired LVEF relative to the non-fibrosis group （P < 0.05）. The heart failure group also demonstrated higher serum concentrations of these biomarkers， along with lower CTRP3 and reduced LVEF， compared to the non-heart failure group （P < 0.05）. Serum miR-210 and TSG-6 levels were positively correlated with PⅢNP and NT-proBNP （P < 0.05） and negatively correlated with LVEF （P < 0.05）. Multivariate analysis revealed that elevated serum miR-210 （OR = 2.065， 95%CI： 1.116 ~ 3.821） and TSG-6 （OR = 1.047， 95%CI： 1.013 ~ 1.083） were independent risk factors for heart failure in DCM patients （P < 0.05）， whereas higher CTRP3 levels （OR = 0.911， 95%CI： 0.849 ~ 0.978） were associated with a protective effect （P < 0.05）. The sensitivity of serum miR-210， TSG-6， and CTRP3 in predicting heart failure in DCM patients was 72.34%， 74.47%， and 74.47%， respectively， with specificities of 62.86%， 62.86%， and 68.57%， yielding AUC values of 0.669， 0.712， and 0.759， respectively. Conclusions Serum levels of miR-210 and TSG-6 are elevated， whereas CTRP3 levels are reduced in patients with DCM. These biomarkers are closely associated with myocardial fibrosis and cardiac function impairment. Moreover， miR-210， TSG-6， and CTRP3 exhibit significant predictive value for the prognosis of DCM.