Objective To explore the distribution and antibiotic resistance of pathogenic bacteria isolated from sputum of patients with acute exacerbation of coexisting chronic obstructive pulmonary disease ( COPD) and bronchiectasis , so as to guide the rational antimi-crobial application in clinical practise .Methods Bacteria culture and drug susceptibility testing were performed for the sputum samples of 98 hospitalized patients with acute exacerbation of coexisting COPD and bronchiectasis from January 2010 to April 2014.Results A total of 66 strains of pathogenic bacteria were isolated in 96 patients, including 52 strains of Gram -negative bacilli(78.8%), 5 strains of Gram-positive cocci (7.6%) and 9 strains of fungi(13.6%).The five predominant Gram -negative bacterial species were P .aerugino-sa(27.3%), Escherichia coli(13.6%), Klebsiella pneumonia (12.1%), Acinetobacter baumannii (10.6%), and Enterobacter cloa-cae(7.6%).The effective antibiotics against Gram -negative bacterial infection in patients with acute exacerbation of coexisting COPD and brochiectasis included carbapenems , cefoperazone/sulbactam, piperacillin/tazobactam and amikacin .All the S.aureus strains in this stuy were sensitive to vancomycin .Conclusion The Gram -negative bacilli are the main pathogens in acute exacerbation of coexisting COPD and brochiectasis , followed by fungi and Gram -positive bacteria .As the problem of bacterial resistance is getting worse , antibiot-ics should be used more rationally according to the distribution of common pathogens and drug resistance trends in the region .