Abstract: Objective: To explore the etiological causes of atelectasis and to assess the value of bronchoscopy in the diagnosis of atelectasis.Methods: Eighty-six patients with atelectasis were examined by bronchoscope,and the results were analyzed.Results: The etiological causes of 86 cases of atelectasis were determined by bronchoscope,with a diagnosis rate of 93.02%.Among the 86 cases of atelectasis,lung cancers accounted for 54 cases,including 40 cases of squamous cell carcinoma,inflammation was observed in 17 cases,tuberculosis in 8 cases,bronchiectasis in 6 cases and foreign body in 1 case.Conclusions: The main etiological cause of atelectasis is lung cancer,with squamous cell carcinoma as the main type.Bronchoscopy is not only of help to the diagnosis of atelectasis but has therapeutical effect as well.