Objective To evaluate the therapeutic effect of Xiao'er Zhixie Paste (XZP) by using the young rat model of chronic diarrhea,and to explore its mechanism.Methods Chronic diarrhea model in young rats was induced by ig senna.Rats were ig with Montmorillonite powder of 1.62 g/kg,XZP of low,medium,and high dose (2.03,4.05,and 8.10 g/kg) for treatment.Loose stools rate,loose stool grade and diarrhea index were determined 1 and 3 d after treatment respectively.The water content of small intestine was measured and blood was collected for testing serum succinate dehydrogenase (SDH),amylase,D-xylose by colorimetric determination,testing serum D-lactic acid,IL-1 β,and TNF-α by Elisa after administration.Results The rate of loose stools in XZP 4.05 and 8.10 g/kg dose group,and diarrhea index in 8.10 g/kg dose group significantly reduced after the first treatment.The loose stools rate of XZP 2.03,4.05,and 8.10 g/kg dose group,diarrhea index,serum D-lactic acid level in 4.05,8.10 g/kg group significantly reduced,and serum D-xylose level in 8.10 g/kg dose group significantly increased 3 d after treatment.However,XZP had no significant effect on SDH,amylase activity and IL-1β,TNF-α levels.Conclusion XZP has obvious therapeutic effect on chronic diarrhea in young rats,the mechanism is to increase improve the absorptive function and permeability of intestinal tract.