Objective To evaluate whether peripancreatic necrosis volume (PNV) is a useful index for predicting the severity of acute pancreatitis (AP), and to compare the predictive value of PNV with the current clinical scoring system and 48 h-Creactive protein (48 h-CRP) for the clinical outcomes of patients with acute pancreatitis. Methods Clinical data of AP patients who were admitted to The First Affiliated Hospital of Naval Medical University (Second Military Medical University) from Jan. 2020 to Jun. 2021 were retrospectively analyzed. PNV was measured manually using Philips-IntelliSpace Portal. Scoring systems (acute physiological and chronic health evaluation Ⅱ [APACHE Ⅱ］, modified Marshall, Ranson, bedside index for severity of acute pancreatitis[BISAP］, Balthazar, and computed tomography severity index[CTSI］scores) were calculated. Receiver operating characteristic (ROC) curves were used to compare the efficacy of PNV with different scoring systems and 48 h-CRP in predicting prognostic parameters such as organ dysfunction, multiple organ failure (MOF), length of hospital stay, intensive care unit (ICU) stay, and complications during hospitalization, infection and necrosis, and requirement of surgery or intervention. Results A total of 150 AP patients were included, and the PNV (ranged from 20.0 to 1 517.5[539.5±413.4］cm³) was measured manually. PNV was positively correlated with the length of hospital stay (correlation coefficient was 0.462, P＜0.05). The area under curve values (95% confidence interval[CI］) of PNV in predicting infection, complications, MOF, ICU admission, and organ dysfunction were 0.73 (0.60-0.85), 0.72 (0.77-0.88), 0.86 (0.76-0.97), 0.90 (0.82-0.98), and 0.88 (0.80-0.97), the sensitivities were 0.72, 0.67, 0.67, 0.63, and 0.81, and the specificities were 0.99, 0.98, 0.75, 0.81, and 0.91, respectively. The analyses of the ROC curves showed that PNV was the best parameter to predict the prognosis of AP compared with the scoring systems or 48 h-CRP. Conclusion PNV may be useful in predicting the severity of AP.