Objective To observe the application effects of magnetic resonance imaging(MRI) and two-dimensional echocardiography (2DE) in the evaluation of cardiac function in patients with idiopathic dilated cardiomyopathy (IDCM), and analyze the correlation with classification of New York Heart Association (NYHA). Methods The clinical data of 78 patients with IDCM were retrospectively analyzed. All patients were given MRI and 2DE. Patients were divided into grade I~II group (n=18), grade III group (n=32) and grade IV group (n=28) according to NYHA classification. The left ventricular function parameters [left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF)] were compared among the three groups by MRI and 2DE. The correlation between the above parameters and NYHA classification was analyzed. Results MRI showed that LVEDV and LVESVin grade I~II group were lower than those in grade III group and grade IV group, and the indexes in grade III group was smaller than those in grade IV group (P<0.05). The LVEF in grade I~II group was greater than that in grade III group and grade IV group, and the index in grade III group was larger than that in grade IV group (P<0.05). 2DE examination showed that LVEDV and LVESV in grade I~II group were lower than those in grade III group and grade IV group (P<0.05), and there was no significant difference between grade III group and grade IV group (P>0.05). The LVEF in grade I~II group was greater than that in grade III group and grade IV group, and the index in grade III group was larger than that in grade IV group (P<0.05). Both MRI and 2DE showed LVEDV and LVESV were positively correlated with NYHA classification, and LVEF was negatively correlated with NYHA classification (P<0.05). Conclusion MRI and 2DE have good correlation with NYHA classification in patients with IDCM, but MRI correlation is better than 2DE, and 2DE is easy to underestimate left ventricular volume, and MRI is more advantageous.