Abstract: OBJECTIVE To analyzed the influencing factors and molecular epidemiological characteristics of severe carbapenem-resistant Klebsiella pneumoniae（CRKP） pulmonary infection. METHODS A total of 375 patients with severe pulmonary infection who were positive for culture of K.pneumoniae in Hainan Western Central Hospital and Sanya People’s Hospital were enrolled in the study, the patients were divided into the CRKP group and the carbapenem-sensitive K.pneumoniae（CSKP） group according to the status of isolation of CRKP. The risk factors for CRKP infection were analyzed, the carbapenemase phenotypes of CRKP were screened by the modified Hodge test, the horizontal transfer of carbapenem genes and drug resistance genes was determined by means of polymerase chain reaction（PCR） and plasmid conjugation test, and the cloning correlation was analyzed by the pulsed field gel electrophoresis（PFGE）. RESULTS Totally 105 strains of non-repetitive CRKP were isolated from 375 patients. Complication with more than 2 types of chronic diseases, length of hospital stay no less than 3 weeks before infection, more than 2 types of indwelling tubes, use of carbapenems no less than 1 week and use of the third or fourth generation of cephalosporins in the past 3 months were the independent risk factors for the CRKP infection（P＜0.05）. Among the 105 strains of CRKP, 91（86.67%） were positive for the modified Hodge test. Among the 91 strains of CRKP positive for the modified Hodge test, 79（86.81%） strains carried with bla_KPC-2 gene, 33（36.26%） strains carried with bla_NDM-1gene, 3（3.30%） strains carried with bla_IMP-4 gene, and bla_VIM or bla_OXA gene was found. All of the 91 strains of CRKP were negative for serotypes, while 87 strains carried with virulence gene uge, 88 strains carried with mrk D, 84 strains carried with ybt S, 86 strains carried with kpn, and 91 strains carried with ent B.The plasmid conjugation test for the 91 strains of CRKP was successful. PFGE clustering analysis showed that the 91 strains of CRKP could be divided into 7 clonotypes（ST）, 58（63.74%） of which carried with ST11. CONCLUSION There are a variety of risk factors for the CRKP infection in the patients with severe pulmonary infection, carrying with bla_KPC-2 and bla_NDM-1 genes is the main mechanism, ST11 is the predominant clonotype, and it is necessary to put forward prevention and control measures as early as possible.