OBJECTIVE To analyze multi-drug resistant Acinetobacter baumannii(ABA) outbreak of nosocomial infection in the respiratory intensive care unit(RICU),to explore effective measures for prevention and control.METHODS In RICU on April 3 to 30 2009,patients under mechanical ventilation in the respiratory tract with MDRABA were conductd epidemiological surveys.RESULTS On 27 consecutive days,six cases occurred in mechanical ventilation in patients with lower respiratory tract MDRABA infection,of which 5 patients were cured;6 cases of lower respiratory tract of patients in sputum specimens isolated the same resistance spectrum MDRABA.CONCLUSIONS Medical personnel lack the consciousness of washing their hands.Indoor environment,air disinfection machine lack of supervision in mechanical ventilation patients with lower respiratory tract MDRABA,were the main reasons of infection outbreak.Strict isolation of patients should be strengthened,full implementation of hand-washing compliance,education,conventional screening,early intervention to prevent outbreak of hospital infection.