Objective To investigate the effect of Buzhong Yiqi Granules（ BZYQ） in the treatment of diarrhea in rats and explore its mechanisms. Methods The rats were randomly divided into 5 groups: normal control,BZYQ（ low dose,middle dose,high dose）,and Loperamide. Castor oil induced diarrheal model was established and then the antidiarrheal index, small intestine propulsion rate and small intestine volume were observed. Isolated tension measurement perfusion system was used to measure the contraction tension,amplitude and frequency of isolated ileac longitudinal smooth muscle strips of all groups. In addition, the differences in basal current and transmembrane resistance of ileum mucosa of all groups were observed with a short circuit current（ Isc） technology. Results Compared with the normal group,the anti-diarrhea index of middle and high dose of BZYQ groups were significantly increased（ P < 0. 01）, and both intestinal propulsive rate（ P < 0. 01） and intestinal fluid volume decreased（ P <0. 01）. Meanwhile,the contraction tension,amplitude and frequency of isolated ileac longitudinal smooth muscle strip of BZYQ middle dose group were significantly decreased（ P < 0. 01）. Furthermore,basal current was significantly reduced（ P < 0. 01） and transmembrane resistance of ileum mucosa enhanced（ P < 0. 05） in BZYQ. No significant difference in above results was found between BZYQ group and loperamide group（ P > 0. 05）. Conclusion BZYQ has certain curative effect on diarrhea in rats by modulating intestinal motility and secretion.