The mechanism and pathology of patients with severe acute pancreatitis with non-occlusive mesenteric ischemia (NOMI) are still unclear. Currently, there are some reports that vasoconstriction associated factors (angiopoietin-2, endothelin-1 and VEGF et al. ) have important role in the development of NOMI with severe acute pancreatitis. In our experience, one of characteristic pathological findings of NOMI is the non-consecutive enterointestinal damage. The diagnosis of NOMI is not easy in the early stage, so we attempt to use hepatic perfusion CT to diagnose it. Hepatic perfusion CT can evaluate hepatic portal flow (HPF) and hepatic arterial flow (HAF), separately. In our study, HPF of acute pancreatitis patients with NOMI was significantly slower than those without NOMI. Therefore, evaluation of hepatic perfusion in the early stage might be extremely helpful in the diagnosis of NOMI. In this paper, we would like to report the mechanism, pathology, diagnosis and treatment of NOMI in severe acute pancreatitis.