Objective：To investigate the effect of substance P（ SP）/ NK1 receptor pathway on contractile function of isolated pyloric smooth muscle strips by detection gastrointestinal function and SP expression during experimental gastric ulcer. Methods：62 SD rats were divided into normal group（n=6），saline control group （n=24） and ulcer group （n=32）. Gastric ulcer model were used acetic acid-induced in rats，and the ulcer area was measured. Gastric emptying rate and intestinal propulsive function were observed by intragastric administration of methyl cellulose. The effects of SP and NK1 recepter antagonist on the contractile reactivity of isolated pyloric annular smooth muscle strips with a tension transducer and a multi-channel physiological signal acquisition and processing system. Results：The typical “Ring dike sign”was formed on the 4th day，the ulcer gradually healed from the 10th to 14th day，and the scar tissue was formed on the 28th day. Immunohistochemical results showed that SP positive cells were mainly distributed in fundic gland cells，submucosa and myometrium of gastric mucosa. The integral optical density of SP in ulcer at the 4th，10th and 14th days was significantly lower than that in normal and control groups （P<0.05，P<0.01）. Gastric emptying rate in ulcer group was significantly lower than that in normal group and saline group （P<0.05） . The contractile amplitude of pyloric annular muscle strips in ulcer group was decreased in different degrees compared with that in normal group （P<0.01） ，when NK1 receptor antagonist was added，the contraction amplitude and frequency decreased significantly（P<0.05，P<0.01）. Conclusion：The mechanism of decreased gastrointestinal motility in gastric ulcer is related to SP/NK1 receptor signal pathway.