Abstract： Objective To study the alteration of plasm motilin and vasoactive intestinal peptide of rats with constipation by outlet obstruction. Methods The models of constipation by outlet obstructio were made by constricting the rectum of rats partly,and taking out stitches in vitro to relieve obstructio. The contents of plasma motilin and vasoactive intestinal peptide were measured by radio-immunity analyzing. Results The tunica mu-cosa coil of model group rats were hydropsia,and concomitance with inflammatory cell infiltration. There was no significant difference in the levels of plasma MTL in all groups, but the levels of plasma VIP of model group were significantly lower than normal group (P<0.01). There was no significant difference between model group and relieve obstructio group. Conclusion Constipation by outlet obstruction results in inflammation of tunica muco-sa coli of model group rats,and effects the levels of plasma VIP.