Hemoptysis after chemotherapy for lung cancer is very common, which is considered as tumor metastasis or recurrence, or further deterioration of the disease. There are two common clinical causes: 1) severe necrosis of tumor cells after chemotherapy, causing a small amount of capillary rupture and hemoptysis; 2) lung cancer patients with chronic emphysema or bronchial dilatation may also hemoptysis in the process of chemotherapy. However, if such a situation occurs, we should not panic. First of all, identify the cause and further do chest CT to see if there is pleural effusion or enlarged mediastinal lymph nodes. If the cause is identified first and then treated symptomatically, it can usually be relieved. Clinically, hemoptysis after lung cancer chemotherapy is common in squamous carcinoma, which can usually be treated in time. However, some of them may have ruptured blood in the trachea, and the rupture may lead to acute hemoptysis, which may even be life-threatening, so we must pay attention to this aspect.