How long a lung cancer patient can live with blood in sputum is mainly related to whether the patient belongs to central lung cancer or peripheral lung cancer. Especially, the cytologic classification is closely related to whether the patient belongs to small cell lung cancer or non-small cell lung cancer. Central lung cancer with blood in sputum is mostly squamous cancer, which is common in men who smoke. If it can be detected at an early stage and treated with surgery, its survival period is more than 1 year. If the chance of surgery is lost, the survival period is not more than 1 year. If it is peripheral adenocarcinoma, it is mostly seen in women. Although it is easy to metastasize in early stage, the genetic test suggests gene mutation, and patients can be given gene-targeted drug treatment in early stage, and the survival period is 1-2 years or even longer. If it is small cell carcinoma, the survival period of patients is very short, around 3-6 months. Therefore, once lung cancer is detected in clinic, it is necessary to clarify the cytologic classification as early as possible and give active and effective treatment to prolong the survival period of patients.