Primary lung cancer (hereafter referred to as lung cancer) is one of the common malignant tumors with high morbidity and mortality rates. An important reason for the high mortality rate of lung cancer is that most patients are already in the middle and late stages when they are diagnosed, thus losing the best treatment opportunities. Therefore, if lung cancer can be detected, correctly diagnosed and treated early in its early stages, the mortality rate of lung cancer can be reduced. Recently, the American College of Chest Physicians (ACCP) and the Chinese Society of Respiratory Medicine have published lung cancer treatment guidelines and expert consensus respectively, which provide guidance for early diagnosis of lung cancer. To achieve early detection, early diagnosis and early treatment of lung cancer, it requires the joint efforts of the general public and medical workers. First of all, the general public should care about their own health status. If you have risk factors leading to lung cancer such as age over 50, history of smoking (including passive smoking), history of hazardous occupational exposure, history of chronic bronchitis, chronic obstructive pulmonary disease, diffuse pulmonary fibrosis and pulmonary tuberculosis, and tumor patients in your family, you should have regular health checkups (including chest X-ray, and low-dose chest CT examination if available) and Low-dose CT chest examination), early detection of early lesions. The number of cigarettes smoked per day multiplied by the number of years of smoking is called the “smoking index” for lung cancer. If the number of cigarettes smoked per day is greater than 20 and the smoking age is longer than 20 years, the smoking index is greater than 400 years (or 20 packs of years), and this group of smokers is a high-risk group for lung cancer. For high-risk group, it is not enough to rely on a chest X-ray during annual physical examination, but it is better to have regular low-dose CT examination of the chest to detect lung lesions in time. If symptoms such as irritating dry cough, blood in sputum, bloody sputum, or coughing pattern or coughing habit different from before, weight loss, etc. occur, they should be sufficiently alerted and go to the hospital for chest X-ray or CT examination in time. As medical workers, they should raise their alertness to lung cancer and closely observe high-risk groups. Patients found to be suspected of lung cancer should undergo relevant examinations (chest X-ray, CT, tumor markers, bronchoscopy, etc.) and effective communication and close cooperation among various departments (respiratory medicine, thoracic surgery, medical imaging, pathology, etc.) to clarify the diagnosis as early as possible. Focal changes in the lung greater than 3cm in diameter found during the examination are called lung masses, which have a high possibility of lung cancer and require active management. For lung nodules less than or equal to 3 cm in diameter, both doctors and patients should pay attention to them. A slight negligence may delay the diagnosis of lung cancer. Such lung nodules are not uncommon in clinical practice, but is such a lung nodule lung cancer? How to evaluate the lung nodules? It is currently a tricky issue for clinicians. Because nodules less than or equal to 8mm in diameter are relatively less likely to develop into malignant tumors in the short term, and the tumor multiplication time is longer, nodules less than or equal to 8mm in diameter should be treated differently from nodules larger than 8mm in diameter. For lung nodules larger than 8mm in diameter, previous imaging data should be reviewed and compared first to assess the clinical probability of lung cancer malignancy, and appropriate diagnostic measures (such as CT monitoring, functional imaging, PET/CT, non-surgical biopsy or surgical diagnosis) should be selected according to the condition and patient’s wishes. For substantial nodules less than 8 mm in diameter with high risk of difficult biopsy and resection, and with low possibility of malignancy and metastasis in a short period of time, CT can be considered to be applied for regular follow-up. In conclusion, the early diagnosis of lung cancer requires the joint attention of patients and medical personnel and the multidisciplinary cooperation of hospitals. We believe that through everyone’s efforts, the early diagnosis rate of lung cancer can be improved and the survival rate of patients can be prolonged!