OBJECTIVE：Analyzing the epidemic of drug risistance bacteria with extend spectrum β-lactamase(ESBLs)in children's wards to cut off the transmitting pathway and prevent the outbreak of nosocomial infections in time.METHODS：Samples，including sputum，umbilical secretion，pus，pharyngeal swab，were collected from in-hospital child patients in Departments of Newborn，Respiratory Tract Diseases，Cardiology，Nephrology，Hematology，Pediatric Surgery and ICU，then bacterial cultures and drug susceptibility test were carried out.54 strains of ESBLs E.coli and Klebsiella pneumoniae were isolated and their plasmid profiles were analysed by agarose electrophoresis.RESULTS：The percentages of ESBLs in the above-mentioned departments were 46.3，12.9，5.6，12.9，5.6，11.1，5.6 respectively.In analysis，three types of profiles were found and strains with four types of the same profile concentrated in the Newborn Department.The others were dispersed.CONCLUSION：Nosocomial infections possibly occured in the Newborn Department to some extent.