Objective To analyze the CT and MRI manifestations and their value in diagnosis and treatment of severe acute pancreatitis. Methods The clinical data of 40 patients with severe acute pancreatitis were collected. All patients underwent CT and MRI examination. The imaging features were summarized. The application value of CT and MRI in the diagnosis of severe acute pancreatitis was compared. Results 37 cases of severe acute pancreatitis were diagnosed by CT and a case was misdiagnosed. 36 cases were in accordance with clinical diagnosis and the diagnostic accuracy was 90.00% and sensitivity was 97.30%; 36 cases were diagnosed by MRI and 1 case was misdiagnosed. 35 cases were in accordance with clinical diagnosis. The diagnostic accuracy was 87.50% and sensitivity was 97.22%. The differences in accuracy and sensitivity in diagnosis of severe acute pancreatitis between MRI and CT were not statistically significant (P>0.05). Conclusion CT can clearly show the morphology and structure of pancreas of patients with severe acute pancreatitis, determinate the relationship between the size and range of the lesions and nearby organs and determinate the severity of pancreatic necrosis and the extent of oozing. The repeatability is good and costs is low. It can be used as the first choice for early screening of severe acute pancreatitis.