Lung cancer is one of the most common malignant tumors in the world. According to the information published by WHO in 2008, lung cancer is the most common tumor in the world, both in terms of incidence and mortality. Among them, NSCLC accounts for more than 85% of lung cancers, and most of them are already in advanced stage when they are diagnosed. At present, the 5-year survival rate of lung cancer is only about 15.6%, mainly because about 75% of the patients are already at advanced stage when they are diagnosed, and the prognosis of lung cancer is poor due to insufficient early diagnosis, and the poor prognosis of this patient is due to the failure of early diagnosis. Early diagnosis of lung cancer means early detection and correct diagnosis at the early stage of lung cancer development, early treatment, and reduction of lung cancer death rate. Most of the early stage lung cancer has no symptoms and signs, but the following symptoms should be alerted to the possibility of lung cancer: 1. Persistent irritating cough without or with little sputum. 2.Blood in sputum or hemoptysis. 3.Shortness of breath or wheezing, and limited croup can be detected on auscultation. 4.Fever, antibiotic treatment is not effective. 5.Weight loss without obvious reasons. 6.Extrapulmonary signs of unknown cause and persistent treatment, such as pestle and mortar finger, non-wandering pulmonary joint pain. Male breast enlargement, skin tanning or dermatomyositis, ataxia. 7.Signs of local invasion and metastasis, such as vocal cord paralysis, superior vena cava obstruction syndrome, Horner’s sign, supraglottic pulmonary sulcus syndrome and supraclavicular lymph node enlargement. 8.Unexplained nausea and vomiting, weakness, etc.