Abstract: Objective To investigate the clinical value of Olympus ultra-thin electronic flexible endoscope BF-XP290 combined with the intraluminal ultrasound system in assisting percutaneous transhepatic biliary stricture biopsy. Methods From July to September,2018,12 patients with biliary obstruction underwent endoscopic observation and intraluminal ultrasound of stricture using Olympus ultra-thin electronic flexible endoscope BF-XP290 system combined with luminal ultrasound system in the first Affiliated Hospital of Zhengzhou University,and meanwhile,clamp biopsy was conducted for the lesion through the sheath tube under fluoroscopy. Endoscopic observation,ultrasound image,success rate of endoscopic operation,success rate of biopsy,time of operation,and complications were recorded. The t-test was used for comparison of continuous data between groups. Results All the 12 patients underwent endoscopy and intraluminal ultrasound under intravenous anesthesia,and satisfactory tissue samples were collected. The success rates of operation and biopsy were 100%,and the mean time of operation was 27. 8 minutes. Biliary stricture and tumor-like neoplasms were observed in 10 patients( 83. 3%),and biliary stricture and mucosal bulge were observed in 2 patients; the location of lesions was consistent with the location of obstruction on preoperative imaging. Intraluminal ultrasound showed localized mucosal bulge in 6 patients,even thickening and narrowing of the lumen in 2 patients,and invasion of the outer wall in 9 patients. Clamp biopsy suggested bile duct adenocarcinoma( well-differentiated adenocarcinoma in 7 patients,moderately differentiated adenocarcinoma in 2 patients,and poorly differentiated adenocarcinoma in 1 patient). Two patients( 16. 7%) were found to have biliary stricture with calculus; intraluminal ultrasound showed even thickening of the lumen with an intact outer wall,and biliary clamp biopsy confirmed fibrous connective tissue hyperplasia. There was a small amount of bleeding in the bile duct after operation in all patients( 100%),and no complications such as bile duct perforation,pancreatitis,and massive bleeding were observed.There were significant changes in total bilirubin,direct bilirubin,alanine aminotransferase,and aspartate aminotransferase after operation( t = 4. 38,5. 34,6. 21,and 5. 76,all P < 0. 01). Conclusion The ultra-thin electronic flexible endoscope BF-XP290 combined withthe intraluminal ultrasound system can provide direct-view and wall information of the bile duct with stricture and reduce the incidence rate of complications while ensuring the success rate and positive rate of intra-biliary clamp biopsy,and therefore,it holds promise for clinical application.