ObjectiveTo study transmission characteristics of Acinetobacter baumannii (A. baumannii ) clone and clinical features of infected patients in a respiratory intensive care unit (RICU)，so as to guide the effective prevention and control  of A. baumannii transmission.Methods40 A.baumannii strains isolated from RICU patients were performed homology analysis by pulsedfield gel electrophoresis (PFGE) and cluster analysis，relationship of strains was determined，antimicrobial resistance and clinical data were analyzed. Results40 A.baumannii strains were divided into 11 genotypes(AK)，the main epidemic strains were type A, B and E. The resistant rate to imipenem was the lowest(70.00%)，the next was levofloxacin (77.50%). The average age of 40 infected patients was 67 years old, the average length of hospital stay was 41 days, 12 patients died because of invalid treatment. There was overlapping hospitalization among patients infected with type A and E strains; among patients infected with type B strain,  there was no overlapping hospitalization among the last 6 and first 6 infected patients.  ConclusionThe main epidemic strains of  A.baumannii were type A, B and E，antimicrobial resistant rate is high; the infected patients are with high average age and long length of hospital stay. It is important to reduce the transmission of A.baumannii through rational use of antimicrobial agents, strict aseptic operation, and intensified disinfection and sterilization of hospital environment and medical devices.