To observe the effects of Sennoside A on intestinal motility in rats with colonic slow transit constipation (STC).Methods:Thirty SD rats were randomly divided into five groups：normal control group，model group，Sennoside A group，SennosideA+ZD7288 group and mosapride group.The STC rat model was established with ice water stimulation by gavage.The electrophysiology was used to detect the intestinal electrical activity.Percentage of carbon propelling，contraction amplitude and frequency of the muscle segments in vitro were observed.At the same time，the electrophysiological changes of the colonic muscle strips were observed by using the blockers of HCN1 (ZD7288)，and the data were statistically analyzed.Results:The percentage of carbon propelling in the Sennoside A group was higher than those in the model group，Sennoside A+ZD7288 group and Mosapride group (P<0.05).Compared with the Sennoside A group，the contraction frequency of the muscle segments in the model group，Mosapride group and Sennoside A+ZD7288 group decreased obviously (P<0.05).The contraction amplitude of the muscle segments in the Sennoside A group was higher than those in the model group and ZD7288+Sennoside A group (P<0.05).However，there was no significant difference between the Sennoside A group and the normal control group (P>0.05).Conclusion:Sennoside A could promote colon motility by increasing the contraction frequency and amplitude of the smooth muscle.The prokinetic effect of Sennoside A is better than mosapride.HCN1 may be a target ion channel of sennoside A.