ObjectiveTo explore the distribution and antimicrobial resistance of pathogens causing lower respiratory tract infection in patients, and provide basis for rational choice of antimicrobial agents in clinic. MethodsAll bronchoalveolar lavage fluid specimens in a hospital from January 1, 2013 to December 31, 2014 were performed culture, antimicrobial susceptibility testing of isolated strains was performed with KirbyBauer method. ResultsA total of 999 strains were isolated from 7 702 bronchoalveolar lavage fluid specimens, 398 (5.17%), 326 (4.23%), and 275（3.57%） strains were bacteria, fungus, and Mycobacterium respectively. The main bacteria were Pseudomonas aeruginosa(P. aeruginosa, n=97), Acinetobacter baumannii(A. baumannii, n=87), Klebsiella pneumoniae(K. pneumoniae, n=62), Staphylococcus aureus(S. aureus, n=44), and Haemophilus influenzae (n=28); the main fungi were Candida albicans (n=161), Aspergillus fumigatus (n=41), and Aspergillus flavus(n=38); the main Mycobacterium were Mycobacterium tuberculosis(n=271). Antimicrobial susceptibility testing results showed that resistance rates of P. aeruginosa to the commonly used antimicrobial agents (except ticarcillin/clavulanic acid and levofloxacin) were all<30.00%. Resistance rates of A. baumannii to ampicillin/sulbactam, imipenem, amikacin, gentamicin, and tobramycin were all >80.00%, but to the other commonly used antimicrobial agents were 36.84%-60.53%. Among 62 strains of K. pneumoniae, 20 were extendedspectrum βlactamases(ESBLs)producing strains. Antimicrobial resistance rates of ESBLsproducing strains were obviously higher than nonESBLsproducing strains. Among 44 S. aureus strains, 26 were methicillinresistant S. aureus (MRSA), resistance rate of S. aureus to penicillin was 97.73%, to vancomycin, teicoplanin, and linezolid were all 0, to the other antimicrobial agents were 9.09%-61.36%. ConclusionBacteria is the major pathogen causing lower respiratory tract infection in hospitalized patients, but fungus and Mycobacterium can not be ignored. Resistance rates of P. aeruginosa to commonly used antimicrobial agents is relatively low, but resistance of A. baumannii is more serious.