Bloody sputum of lung cancer has various manifestations, and blood in sputum is the most common manifestation, which is also the most common clinical manifestation of early stage lung cancer, and the blood is bright red, or it can be small blood clots. Patients with tumor invading small blood vessels will have hemoptysis, which can be bright red hemoptysis or dark red hemoptysis, and dark red hemoptysis represents old hemorrhage. Other patients may have brick-red bloody sputum, which is caused by the combination of specific infections on top of lung cancer. For example, some patients may have brick-red bloody sputum when combined with Klebsiella pneumoniae infection. The tumor of the patient may invade the large blood vessels and cause blood vessel rupture, resulting in lethal hemoptysis with bright red blood. Besides, the clinical manifestations of lung cancer include coughing sputum, fever, chest pain, chest tightness, dyspnea and so on.