Abstract: OBJECTIVE To observe the bile aerobic bacteria in patients with biliary tract infection after endoscopic retrograde cholangiopancreatography（ERCP） and their drug susceptibility. METHODS A total of 85 patients with biliary tract infection after ERCP who were treated in the Department of Gastroenterology at Hanyang Hospital Affiliated to Wuhan University of Science and Technology from Jan 2015 to Jan 2020 were selected as the research subjects. The bile specimens were taken from ERCP operation and were divided into positive and negative groups according to the results of bile bacterial culture. Meanwhile, drug susceptibility and resistance genes of aerobic bacteria were analyzed. RESULTS Among the 85 patients, 62 cases were positive for bile culture, and 23 were negative, the number of abnormal hemograms in the positive group was significantly higher than that in the negative group（P＜0.05）. A total of 68 strains of aerobic bacteria were detected, of which 51 strains of Gram-negative bacteria accounted for 75.00%, and 17 strains of Gram-positive bacteria accounted for 25.00%, mainly Escherichia coli, Klebsiella pneumoniae and Enterococcus faecails. The resistance rates of E. faecalis to penicillin G and levofloxacin were higher than 40%, and it was more sensitive to vancomycin, nitrofurantoin and teicoplanin. The resistance rates of E. coli and K. pneumoniae to cefazolin and cefotaxime were higher, and both were more sensitive to imipenem, meropenem and tigecycline. The main drug resistance genes detected in E coccus were ant（4 c, 4 d）, aac（6 c）/aph（2 d）, ant（2 d）-Ⅰ, TEM, and aph（3 c）-Ⅲ. The main resistance genes detected in E. coli were TEM, aac（6 c）/aph（2 d）, and ant（6）-Ⅰ. CONCLUSION Gram-negative bacteria was the main bile aerobic bacteria in patients with biliary tract infection after ERCP. Most of the pathogenic bacteria detected were multi-drug resistant. Sensitivity test analysis was of great guiding significance for rational use of antibiotics in clinical practice.