Abstract: Objective To investigate the value of 1.5T cardiac magnetic resonance imaging in the study of left ventricular global function and myocardial fibrosis in primary dilated cardiomyopathy (DCM). Methods Selected Twenty seven patients were admitted to the Department of Radiology, the Second Affiliated Hospital of Anhui Medical University from June 2016 to June 2018 with dilated cardiomyopathy (DCM) and 27 healthy volunteers were collected. All subjects were examined with conventional 1.5T cardiac magnetic resonance plain scan and gadolinium enhancement. Left ventricular short axis film (plain scan) and delayed enhanced cardiac magnetic resonance images (DE-MRI) were obtained. The left ventricular function indices (standardized body surface area) and myocardial delayed enhancement images were obtained. The functional indices included left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular myocardial mass (LVMM), left ventricular ejection fraction (LVEF), and left ventricular peak ejection rate (LVPER), left ventricular peak filling rate (LVPFR) and interventricular septal thickness (IVSTD), etc. The differences of values between the two groups were compared. In DCM group, the above values were divided into DE-MRI (+) group and DE-MRI (-) group according to delayed enhancement, and the differences between the two groups were compared. Results ①The LVEF, LVPER, LVPFR and IVSTD of the patients group were lower than those of the healthy control group, and the remaining indicators were significantly higher than those of the healthy control group, with statistical significance; ②The LVMM and LVESV of DE-MRI (+) group were higher than those of DE-MRI (-) group, while LVEF decreased in DE-MRI (+) group, with statistical significance. There was no difference among the other groups. ③Delayed myocardial enhancement was found in 17 patients (62.96%) with 153 segments, including 101 segments (66.01%) between the muscles, and the ventricular septal wall (12 cases, 70.58%) were the main sites. Conclusion ①Decreased global left ventricular function in DCM is accompanied by left ventricular myocardial fibrosis, and the distribution of septal wall is significant. ②LVMM can roughly evaluate the degree of myocardial fibrosis (MF) in DCM.