【Objective】 To explore the effect and security of bronchoalveolar lavage (BAL) on infected atelectasis in children. 【Methods】 The inpatients who diagnosed with infected atelectasis were retrospectively analyzed in our hospital, the control group(n=40) received only conventional therapy and antibiotic was based on Sputum culture and drug susceptibility, while the treatment group(n=40) received additional bronchoalveolar lavage via fibrobronchoscopy, both the treatment course were 4 weeks,then after 4 weeks the symptoms and signs, X ray or CT changes in the lung were observed, at the same time,the complications were also observed. 【Results】 The effect in the treatment group was better than in the control group, there was significantly difference between the two groups(P<0.01), The symptoms and signs recovered sooner in the treatment group than in the control group (P<0.01), X ray or CT changes in the lung recovered sooner in the treatment than in the control group (P<0.05)after 4 weeks. The incidences of complications in the treatment group were, hemorrhage 2.5%, fever 5%, laryngeal edema 2.5%, bronchospasm 2.5%, cyanosis 2.5%. 【Conclusions】 Bronchoalveolar lavage on infected atelectasis early can improve the transepithelial liquid to be transported, promote to absorbed the inflammation as early as possible and to reexpand the lung. The effect and security of BAL is definite and it deserves promotion.