Blood in cough sputum is not necessarily lung cancer, but it is important to rule out the possibility of lung cancer, especially in middle-aged or older men who have been smoking for a long time. CT plain and enhanced examination of the lungs must be done to find out whether there are any occupying lung lesions. If there is an occupying lung lesion, timely diagnosis can be made by puncture examination or fiberoptic bronchoscopy to obtain pathological tissue. Cough with blood in sputum can also be seen in tuberculosis, bronchitis, bronchial dilatation, fungal infection, etc. The specific diagnosis should be made by combining clinical manifestations, imaging features, concomitant symptoms, response to treatment, etc. If fever, cough, yellow sputum, or blood in sputum may be inflammation of the lung, the inflammation will dissipate and be absorbed rapidly after anti-infection treatment, and the cough and blood cough will disappear. In contrast, tuberculosis is often accompanied by low fever, night sweats and pleural effusion, and anti-tuberculosis treatment is effective. History of bronchial dilatation will cause recurrent episodes of cough and blood in sputum, and the diagnosis can be confirmed when bronchial cystic dilatation is detected by lung CT.