1.Symptoms and signs: The most typical symptoms and signs of lung cancer are the direct symptoms brought by lung tumor, including blood in sputum, coughing up blood, chest tightness, chest pain, dyspnea, hoarseness, choking on water and fever. For example, brain metastasis may cause dizziness, headache and blurred vision, bone metastasis may cause bone pain and pathological fracture, and lymph node metastasis may cause new lumps on the body surface. It should be noted that most lung cancer patients do not have any symptoms or signs. 2.Imaging diagnosis: Commonly used include localized lung: chest fluoroscopy, chest X-ray, chest CT, diagnosis of extra-pulmonary metastasis: head MRI, whole-body bone scan, neck and abdomen ultrasound or CT. It is worth mentioning that whole-body PET-CT has emerged in recent years, which can judge the tendency of benign or malignant lesions found, and the accuracy rate can be as high as 95%. 3.Pathological diagnosis: The methods to obtain pathology of lung cancer include tracheoscopy, CT or B ultrasound guided percutaneous mass aspiration, mediastinoscopy, thoracoscopy or open-heart surgery, and lymph node biopsy can be performed if the patient has superficial lymph node metastasis. Pathological diagnosis is the “gold standard” for lung cancer diagnosis, other diagnoses can only say “leaning toward lung cancer”, and only after the pathology is clearly diagnosed can the hat of “lung cancer” be finally put on.