Abstract: OBJECTIVE To investigate the changes of inflammatory indexes and spiral CT imaging in patients with severe acute pancreatitis (SAP). METHODS A total of 80 patients with acute pancreatitis admitted to our hospital from Feb. 2015 to Jul. 2017 were selected, and were divided into infection group (46 cases) and uninfected group (34 cases). The differences of infection inflammatory indexes and the changes of spiral CT imaging were compared between the two groups. RESULTS The serum white blood cell count (WBC), C- reactive protein (CRP), procalcitonin (PCT) and Hematocrit (HCT) of infection group were (5.27±0.52)×10⁹/L, (157.31±25.30) mg/L and (5.11±0.62) μg/L and (59.26±25.61)%, which were significantly higher than of uninfected group (all P<0.05). There was no significant difference in the red blood cell count (RBC) between the two groups. The Ranson score of the patients in infection group was significantly lower than that in uninfected group, and the APACHE II score was significantly higher than that of uninfected group (P＜0.001). The spiral CT examination of pancreatic volume increasing, pancreatic fat layer blurring and the surrounding exudation increasing, single or multiple areas of necrosis and pancreatic juice, and flaky necrosis and bubble syndrome of infected group were all significantly more than those in uninfected group (P<0.05). CONCLUSION In severe acute pancreatitis patients with infection, inflammation and other indicators of infection of WBC, HCT and PCT increase significantly and the spiral CT imaging can show pancreatic volume increasing accompanied by pancreatic fat blurring and peripheral leakage, multiple regional pancreatic juice retention, bubble signs, and flaky necrosis. It has important guiding significance for the clinical diagnosis of severe acute pancreatitis.