The treatment for lung atelectasis after left upper lobectomy includes medication, closed chest drainage, etc., together with pulmonary function rehabilitation exercise to promote lung reopening, and the use of medication should be in accordance with the doctor’s instructions. Lung surgery patients, long-term bedridden, shallow breathing, increased secretions in the lungs, sputum removal difficulties, etc., are prone to lung infection, causing inflammatory reaction, resulting in localized adhesion of lung tissues, the formation of pulmonary atelectasis. It is necessary to actively fight infection, such as the use of cephalosporin antibiotics, ceftriaxone, etc., and the use of phlegm transforming drugs, such as ambroxol hydrochloride oral solution. Postoperatively, chest drains are placed to drain fluid or gas from the chest cavity, and pulmonary function rehabilitation exercises, such as encouraging coughing, blowing balloons, blowing bubbles, and getting out of bed, etc., are carried out to promote lung reopening. If lung expansion occurs after left upper lobectomy, it is recommended that the patient should seek medical treatment in time and cooperate with the doctor for active diagnosis and treatment, so as to avoid delaying the condition.