Abstract:【Objective】 To observe the change of sphincter of Oddi (sphincter of Oddi, SO) pressure before and after the EST (endoscopic sphincterotomy,EST) procedure for low end of the bile duct with benign stenosis. 【Methods】The duodenal pressure, common bile duct pressure, SO basal pressure, contraction amplitude, contraction frequency changes were detected in 18 patients with benign stenosis in the lower end of the bile duct in EST before and after the application of sphincter of Oddi 【Results】 The lower end of the bile duct after endoscopic sphincterotomy benign stenosis SO pressure was reduced 【Conclusion】 Endoscopic sphincterotomy patients with benign stricture of the lower end of the bile duct SO pressure reduction can improve the symptoms of patients due to the SO dysfunction.