Objective To investigate the distribution and antibiotic resistance of pathogenic bacteria in PICU and to provide evidence for use of antibiotics rationally.Methods All the basic clinical features and pathogenic bacteria isolated from patients in PICU of our hospital from October 2009 to September 2012 were analyzed retrospectively.Results A total of 672 pathogenic bacterial strains were isolated (positive rate 16.7％ 672/4 020),75.1％ and 24.9％ were gram negative bacteria and gram positive bacteria,respectively.Pseudomonas aeruginosa was the most common bacteria isolated in gram negative bacteria,followed by Klebsiella pneumonia and Escherichia coli in this order.And Staphylococcus was the main strain in gram positive bacteria.Positive specimens were mainly from lower respiratory tract and bloodstream infection.Most Staphylococcus were resistant to penicillin,oxacillin and erythromycin but susceptible to vancomycin,teicoplanin and linezolid.Gram negative bacteria were resistant to ampicillin,ampicillin-sulbactam,piperacillin and cephalosporin,but susceptible to imipenem,cefoperazone-sulbactam,piperacillin-tazobactam,ciprofloxacin and amikacin.Conclusion Gram negative bacteria is the prevalent strains in PICU of our hospital,Pseudomonas aeruginosa,Klebsiella pneumonia and Escherichia coli are common bacterium isolated.Most isolates are highly drug-resistant.Analysis of pathogenic bacteria and drug-resistance surveillance are of vital importance to guide treatments for critically ill children and reduce drug-resistant bacterial strains.