Abstract: Objective To investigate the correlation between non-alcoholic fatty liver disease (NAFLD) and epicardial fat thickness (EAT) in patients with type 2 diabetes mellitus (T2DM). Methods A total of 50 cases of T2DM with NAFLD were selected from December 2017 to July 2018 in the Second Affiliated Hospital of Dalian Medical University. And 47 cases of T2DM without NAFLD were selected as the control group（group A）. Ultrasonography and transthoracic echocardiography were performed in the two groups. NAFLD participants were further divided into mild（group B）, moderate（group C） and severe（group D） according to the 2-dimensional ultrasonography. EAT were obtained at the same time and the correlation was analyzed. Total cholesteroi(TC), triglyceride(TG), low-density lipoprotein(LDL), high-density lipoprotein(HDL), glycosylated hemoglobin Alc (HbA1c), fasting plasma glucose(FBG), 2h postprandial glycemia (2hPG), body mass index(BMI), and waist circumference were measured．Results The EAT values of group B, C and D were higher than those of group A (P<0.05). Groups C and D were higher than group B (P<0.05), and group D was higher than group C (P<0.05). Spearman correlation analysis indicated EAT and NAFLD severity (r=0.782, P<0.001), HbA1c (r=0.679, P<0.001), TG (r=0.649, P<0.001), BMI(r=0.601, P< 0.05) and waist circumference (r = 0.564, P < 0.05) showed a positive correlation. HbAlc, TG and BMI were independent predictors of EAT in multiple linear regression analysis. Conclusions When T2DM patients with NAFLD, their EAT thickness is significantly thickened, and EAT increases with the severity of NAFLD. There is a positive correlation between them. Therefore, ultrasound technology can objectively evaluate the abnormal changes of EAT in T2DM patients with NAFLD with clinical significance.