Objective To investigate the role of glycemic variability in the prognosis evaluation of severe acute pancreatitis. Methods A prospective study was conducted in patients with severe acute pancreatitis admitted to the Department of Critical Care Medicine, Hainan Provincial Nongken General Hospital from January 2013 to December 2015. Patients were divided into survival group and death group according to whether they survived for 28 days. The average value of blood glucose (GLU_AVE), standard deviation of blood glucose (GLU_SD), coefficient of variation of blood glucose (GLU_CV), glycemic lability index (GLU_GLI), mean amplitude of glycemic excursion (GLU_MAGE), APACHEⅡ score and SOFA score were compared between the two groups. The predictive value of glycemic variability on the prognosis of patients with SAP was explored by the receiver operating characteristic curve. Results 89 patients with SAP divided into survival group (n=71) and death group (n=18). Compared with the survival group, the APACHE Ⅱ score, SOFA score and GLU_MAGE, GLU_GLI, GLU_CV, GLU_SD in the death group were significantly higher than those in the survival group(P﹤0.05). The area under ROC of GLU_MAGE, GLU_GLI, GLU_CV, GLU_SD, GLU_AVE were 0.845, 0.807, 0.755, 0.750 and 0.733, respectively. Conclusion The glycemic variability has a good prognostic value in patients with severe acute pancreatitis, GLU_MAGE is a sensitive predictor of 28-day mortality.