Lung cancer usually has no obvious symptoms in the early stage, and corresponding symptoms, such as cough, bloody sputum, chest tightness, etc., will appear only after the disease has developed to a certain stage. Lung cancer, also known as primary bronchopulmonary cancer, refers to malignant tumors originated from bronchial mucosal epithelium or alveolar epithelium. Early stage lung cancer usually has no symptoms and is mostly found when chest X-ray or chest CT examination is performed. With the development of tumor cells, patients gradually develop cough, bloody sputum, chest pain, fever and shortness of breath. Cough is a common symptom of lung cancer, and irritating cough often occurs when the cancer grows in the larger bronchial tubes. When the cancer continues to grow and obstructs the bronchial tubes and secondary lung infection, increased sputum volume and purulent sputum may appear. Bloody sputum is common in central lung cancer, which is usually sputum with blood spots, blood filaments or intermittent small amount of hemoptysis, while massive hemoptysis is rare. Early detection and early treatment of lung cancer is the key to improve the cure rate. Regular screening should be conducted for high-risk groups, such as those with a history of smoking, a history of malignant tumors, and a family history of lung cancer.