This paper is to explore changes of intestinal mucosal barrier, intestinal flora, and bacterial translocation in rats with severe acute pancreatitis (SAP). Twenty four male SD rats were randomly divided into the control group (n=10) and the experimental group (n=14). The model of severe acute pancreatitis of rats was induced by the method of injecting adversely 5% sodium taurocholate into the common biliary-pancreatic duct. All of the rats were killed after 24 hours and the level of the serum amylase and the plasma endotoxin was determined after that. The pathological changes of pancreas and small intestine were observed through hematoxylin-eosin staining (HE staining) and the abdominal viscera bacterial translocation rates were tested. With the method of real-time polymerase chain reaction (RT-PCR) the quantity of the intestinal flora was analyzed. In the control group, the level of Escherichia coli, Lactobacillus and Bifidobacterium were 2.08±1.29, 11.04±7.55 and 12.21±4.95, respectively. On the contrast, the level of Escherichia coli in the cecum contents was much higher (9.72±3.58, P < 0.01), while the Lactobacillus number was decreased significantly (0.67±0.34, P < 0.01), and the Bifidobacterium number was also decreased (4.59±3.42, P < 0.05) in the experimental group, so the ratio of Bifidobacterium/Escherichia coli was reversed. Besides, in the experimental group, the plasma endotoxin positive rates and the bacterial translocation rates were much higher (P < 0.01 or P < 0.05) and the pathology scores of pancreas and small intestines were also significantly higher (P < 0.01) than those in the control group. These results indicated that in severe acute pancreatitis rats, the intestinal mucosal barrier was severely damaged and the dysbacteriosis occurs in the intestinal canal. And these might relate to the occurrence and development of multiple organ infection.