Objective To analyze the bacterial spectrum and key clinical factors associated with biliary tract infections following percutaneous transhepatic cholangial drainage (PTCD) for malignant obstructive jaundice (MOJ). Methods This retrospective study comprised patients with MOJ who were treated with PTCD from 1st June 2016 to 31st December 2020. Patient clinical data, development of postprocedure biliary tract infections, spectrum of pathogenic bacteria, and drug sensitivity were analyzed, focusing on antibiotic drug resistance and identifying key associated risk factors for postoperative biliary tract infections. Results Of the 528 study patients, 80 were diagnosed with postoperative biliary tract infections, 58 of whom had pathogenic bacteria detected in their bile samples. A total of 90 strains of pathogenic bacteria and 3 strains of fungi were detected; the top 4 were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecium, and Pseudomonas aeruginosa. By univariate analysis, a positive bile culture following PTCD was closely correlated with both the location and degree of preoperative obstruction and the preoperative bilirubin level. Moreover, the results of logistic regression analysis concluded that complete obstruction and a high preoperative total bilirubin level prior to PTCD were independent risk factors for a positive bile culture following PTCD. Conclusion Biliary tract infections following PTCD for MOJ were principally due to Escherichia coli, and bacteria in the bile were statistically more likely to be detected in patients with complete obstruction and high preoperative bilirubin levels.