OBJECTIVE To analyze the risk factors of respiratory tract infection by Stenotrophomonas maltophilia and its resistance to common antibiotics so as to guide clinical prevention and treatment.METHODS Thirty two patients of respiratory tract infection by S.maltophilia were examined.RESULTS Among them,the ratio of susceptivity of S.maltophilia to compound sulfamethoxazole was 87.5%,to levofloxacin was 78.1%,and to ticarcillin/clavulanic acid was 81.2%,but the ratio of resistance of S.maltophilia to imipenem was 100.0%,and it was also high to aminoglycosides and cephalosporins.CONCLUSIONS The old age,serious underlying diseases,many kinds of antibiotics used,infection in hospital and the use of glucocorticoids are the main risk factors of the respiratory tract infection by multiresistant S.maltophilia.