When a lung cancer patient vomits blood, it may come out because of hemoptysis, or it may affect the digestive tract, and what comes out from the digestive tract is called vomiting blood. So whether it is rupture of bronchial artery or gastrointestinal bleeding, further examination is needed to clarify. However, this situation is definitely not good, which may indicate that the disease is relatively advanced. Generally, lung cancer belongs to a kind of malignant tumor of the respiratory system, which itself will cause coughing, coughing up sputum and hemoptysis. Generally, through comprehensive treatment such as radiotherapy, chemotherapy and targeted drugs, it can control the condition and prolong the survival period. However, if there are multiple metastases in the gastrointestinal tract, esophagus, and mediastinum, it may cause gastrointestinal hemorrhage and vomiting of blood. The only way to relieve the symptoms is to apply hemostatic and acid-suppressing drugs, or to apply interventional methods to stop bleeding, and to watch while treating the disease.