Objective To study on the Stenotrophomonas maltophilia infection in tumour patient in order to use drugs in experience.Method The API 20 NE and ATB susceptibility were used to detected the Stenotrophomonas maltophilia.Results There were 42 strains Stenotrophomonas maltophilia detected from respiratory path samples.It showed they had the lowest resistant rate to Ciprofloxacin(10.3%),and had lower to ceftazidime(13.8%) and piperacillin/tazobactam.They had nature resistant to imipeneum.Conclusions Stenotrophomonas maltophilia played a main pole of infection in respiratory path,especially in nosocomial tumour patient.They had sever multiple resistance.It was necessary for clinical laboratory to monito before using drugs.