Lung nodules are one of the most common manifestations of lung imaging, and the main clinical task is to diagnose whether these nodules are benign or malignant lesions, but it is difficult to confirm the diagnosis. In our clinical work, we often encounter patients with CT films looking for someone to look at them, hoping to have a statement, but sometimes it is difficult to have an accurate judgment by reading the films and other methods are needed to assist in the diagnosis. I will explain the knowledge of isolated nodules in the lung below. Isolated pulmonary nodules are nodular lesions in the lung that are solitary, ≤30 mm in diameter, and surrounded by normal lung tissue, and are divided into small nodules (<1 cm) and large nodules (1-3 cm) based on the diameter of the nodule. In clinical practice, isolated nodules in the lung are a common clinical manifestation and a common imaging manifestation of lung cancer, and the treatment options for nodules of different nature are very different. The nature of isolated nodules in the lung can be divided into malignant and benign, with malignant rate accounting for about 73% and benign rate about 27%. Common malignant nodules include: lung cancer, lung lymphoma; common benign nodules include: pulmonary tuberculosis, pneumonic pseudotumor, pulmonary hemangioma, pulmonary fibroma, etc. The nature of isolated nodules in the lung determines the treatment measures and patient's prognosis, therefore, corresponding examination methods are needed to make effective and accurate diagnosis of lung nodules, and the common methods are: Chest CT and enhancement examination: Chest CT can accurately locate the nodules and make preliminary judgment based on the CT plain and enhancement performance and characteristics of the nodules, but the qualitative diagnosis of the nodules has limited accuracy. Fiberoptic bronchoscopy and sputum exfoliative cytology: It is of great significance when the tumor invades the bronchus and can make qualitative diagnosis with a high positive rate, but it is limited in the diagnosis of small isolated nodules in the lung and the positive rate is not high. Positron emission tomography (PET/CT): from the principle of tumor cell metabolism, detecting tumor, has greater sensitivity and accuracy than ordinary CT, but also cannot confirm the diagnosis by this method, and is expensive, and is not recommended as a mandatory test. CT-guided percutaneous lung mass aspiration biopsy: Through the guidance of CT, some tumor tissues are removed by a puncture needle for pathological examination, which has a high diagnostic accuracy, but there is a certain rate of leakage and misdiagnosis. Many patients have doubts about the puncture and worry about the increased risk of metastasis. It is generally believed that percutaneous puncture biopsy does not affect the prognosis of patients. Thoracoscopic surgical biopsy: Compared with traditional open-heart surgery, thoracoscopic surgery has the advantages of less injury, adequate visual field exposure, clear images, clean resection, accurate characterization, and fewer postoperative complications. Moreover, for benign small pulmonary nodules, this minimally invasive surgery is used to obtain a pathological diagnosis while also removing the lesion with minimal trauma, especially removing the patient's severe psychological burden and improving the patient's quality of survival. Thus, this method has many advantages and is a good means of combining diagnosis and treatment. The disadvantage is that it requires hospitalization for surgery. Through the above examination, a clearer diagnosis of isolated nodules in the lung can be made, which is conducive to the development of a reasonable treatment plan to achieve a cure for the disease.