Objective To analyze the drug resistance in clinical isolates of Serratiamarcescens of conventional treatment and carbapenemases,guiding the clinical rational drug use.Methods 106 strains of Serratiamarcescens from 2009~2012 year the clinical isolation,K-B disk diffusion susceptibility test,the modified Hodge method for screening the carbapenemase, Whonet statistical analysis.Results Serratia marcescens in sputum,secretions,swallow swab,urine samples were isolated 89 strains (84.1%),4 strains (3.8%),3 strains (2.8%)and 3 strains (2.8%).Serratiamarcescens resistant to ampicillin and cefazolin rate more than 90%,to aztreonam,cefepime,ceftazidime,piperacillin/tazobactam and Cefoperazone/sulbactam, drug resistance rate was 10%~22%,to amikacin,ciprofloxacin and imipenem were lower than 10%.Imipenem the resistant strains in 4 strains,the modified Hodge test positive 3 strains,the positive rate was 2.8%.Conclusion Serratiamarcescens extensively drug-resistant strains,the resistant mechanism is very complex,the institute has appeared carbapenemase produ-cing strains,clinicians should be based on the drug sensitivity test results.