Objective To investigate the effects of Chaishao Chengqi Decotion on intestinal microbiota and intestinal mucosal lesion in severe acute pancreatitis(SAP).Methods 46 Patients with SAP were randomized into two groups.Routine medical management was initiated in two groups.The treatment group received Chaishao Chengqi Decotion for 1 week.The plasma concentrations ofDiamine Oxidase (DAO),D-lactate were detected and changes of microflora were evaluated by bacterial culture.Results The levels of DAO in the treatment group (4.65 ±0.82)U/ml were significantly lower than those in the control group (5.66 ±2.17) U/ml (P ＜ 0.05) 7 days after treatment.The levels of D-lactate in the treatment group (10.65 ± 5.24)mg/L were significantly higher than those in the control group (5.42±2.13)mg/L (P＜0.05).Bacterial culture revealed that the amount of bifidobaterium (6.02± 1.42)In/g and lactobacilli (7.21 ± 2.02) In/g were significantly increased when compared to those before treatment (3.74± 1.71)In/g and (4.03 ± 1.79)In/g respectively,while there was imbalance of intestinal microflora to some extent in the control group.Conelusien Chaishao Chengqi Decotion exerted the protective effects on gut barrier function by alleviating the damage of intestinal mucosa and balancing the intestinal microbiota following severe acute pancreatitis.