To introduce a rat model of the conversion of acute edematous pancreatitis (AEP) to necrotizing pancreatitis (ANP). One hundred and seven Sprague-Dawley rats were randomized in three experimental groups as follows: sham operation control group and AEP group and ANP group. AEP was induced by pancreatic duct ligation and exocrine stimulation, ANP was induced same as AEP，but with a large dose of dextran-110 (500mg/kg) intravenously. The serum concentration of amylase increased significantly in AEP group and ANP group. Cytosolic free Ca2+ concentration in isolated pancreatic acinar cells increased consistently after induction of ANP. Homorrhage, parenchymal necrosis and calcium deposits in acinar cells were observed in pancreas in ANP group. Ultrastructural examination showed desquamation and necrosis of the endothelium of the pancreatic capillary in ANP group. These results suggest that ischemia may induce the conversion of AEP to ANP via acinar cell Ca2+ overloading. The rat model would seem to be a suitable animal model for studying aggravating mechanism of acute pancreatitis.