Abstract: OBJECTIVE To investigate the effect of Zengyetang granule on lubricating bowel and promoting defecation in mice. METHODS The condition of feces excretion, the moisture of intestines, and the intestinal propulsion in mice administered with Compound Diphenoxylate to develop a constipation model were observed. The large intestinal propulsion in normal mice were observed. The contractile activity of ileum in normal rats and the effect of intestinal juice secretion of intestinal canal in normal mice were studied in vivo. RESULTS Zengyetang granule could shorten the time of discharging the first stool, increase the defecate amounts(P<0.05 or P<0.01), improve the stool properties, increase the moisture of intestines(P<0.05 or P<0.01), and enhance the intestinal propulsive rate in constipation mice. Zengyetang granule also could enhance the large intestinal propulsive rate in normal mice, promote the contractile activity of ileum in normal rats, and increase the amount of intestinal canal fluid in normal mice (P<0.05 or P<0.01). CONCLUSION The Zengyetang granule has the action of lubricating bowel and promoting defecation, and can be used for the treatment of constipation.