Postoperative pulmonary atelectasis after thymoma is mostly caused by bronchial obstruction and infection. Treatment is mainly by bronchial endoscopy with alveolar lavage and medication. Lung atelectasis is a kind of respiratory dysfunction which is caused by many factors leading to bronchial obstruction, which in turn leads to respiratory difficulties. 1. Bronchial obstruction: post-thymoma pulmonary atelectasis caused by sputum accumulation due to bronchial obstruction can be relieved by endobronchoscopic treatment with alveolar lavage. Put fiberoptic bronchoscope into the patient through nasal cavity or artificial airway under local anesthesia, enter into all levels of bronchial tubes step by step, and wash out the sputum with local “water injection”, and then carry out alveolar lavage after suctioning out the sputum, so as to alleviate the symptom of pulmonary atelectasis. 2. Infection: if the postoperative pulmonary atelectasis of thymoma is caused by infection, azithromycin can be taken as prescribed by the doctor to carry out antibacterial treatment to relieve the symptoms of pulmonary atelectasis. If the lungs persist in pulmonary atelectasis, medical attention should be sought as soon as possible, combined with clinical treatment to avoid progression of the disease.