Objective To study the effects of Jichuan Decoction on plasma substance P（ SP）,interstitial cells of Cajal（ ICC）,colonial motility of model rats with slow transit constipation,to speculate the mechanism of the effectiveness of this drug on slow transit constipation,in order to provide appropriate dosage in clinical treatment. Methods The model of slow transit constipation rats was established and were given small,medium and high doses of Jichuan Decoction respectively,meanwhile,the model group and the blank control group were also established,the stool wet weight,body weight,the contents of plasma SP and intestinal tissue c-kit mRNA were determined,and the results were statistically analyzed. Results The average value of stool wet weight of three Jichuan Decoction groups was higher than that of the constipation model group,and that of the small dose group was statistically different from that of the model group（ P < 0. 05）. The mean weight of rats of Jichuan decoction groups was lower than that of the model group,and there was a statistically significant difference between the medium dose group and the model group（ P < 0. 05）. The first defecation time of the three groups was shorter than that of the model group（ P < 0. 05）. The intestinal motility of three Jichuan Decoction groups was larger than that of model group and there was a statistically significant difference between the medium dose group and the model group（ P < 0. 05）. There was a statistical difference between the high-dose group and model group（ P < 0. 01）. Plasma SP content of model group was lower than that of the three groups of Jichuan Decoction,There was a statistical difference between the high-dose group and model group（ P < 0. 05）. The c-kit mRNA content of intestinal tissues of model group was lower than that of the three groups of Jichuan Decoction,there was a significant difference between the model group and the medium-dose group（ P < 0. 05） and there was a highly significant difference between the model group and the high-dose group（ P < 0. 01）. Conclusion Jichuan Decoction may improve intestinal peristalsis and constipation of rats with STC by affecting SP,ICC content and fecal water content of rats,and theadministration of drugs are dosage dependent within the scope of drug dosage in the test.