Pulmonary nodule is a general term used in diagnostic imaging to describe a single round-like hyperdense image in the lungs with a maximum diameter of less than 3 cm. Although pulmonary nodule-like lesions are relatively common among lung lesions, their diagnosis is one of the more difficult problems. x-ray, CT, magnetic resonance and other non-invasive tests have some significance for diagnosis, but cannot make a clear diagnosis of the nature of the nodule, the peripheral lung nodule routine bronchoscopy biopsy can not reach the lesion site, percutaneous lung puncture biopsy diameter is too small, and the risk of puncture is high, such as the occurrence of pneumothorax after puncture, hemorrhage, or the puncture of a higher chance of failure. The chance of failure is high. Open lung biopsy is too traumatic, slow to recover, and expensive for most patients. Therefore, seeking an optimal diagnostic method is the key to early diagnosis and treatment. The ultrasound small probe technology recently introduced by the Affiliated Hospital of Ningbo University of Medical Sciences allows scanning and biopsy of small nodules in the lungs under almost non-traumatic conditions, avoiding the risk of open lung biopsy, with a diagnostic rate of more than 90%. This technology is currently the world’s most advanced diagnostic and treatment technology for small lung nodules, through a small ultrasound probe with a diameter of 2mm, through the bronchoscope to reach the patient’s lesion area, through the ultrasound probe on the rotating probe for non-invasive scanning, scanning images as we usually do ultrasound can be displayed on the computer to show the size of the lesion area, the nature of the lesion, and then carry out biopsies, brushes, flushes, puncture. All of the above operations are carried out in a tube diameter of 2mm, the patient will not have other discomfort except for a slight cough. At present, small lung nodules have a high rate of underdiagnosis, while lung cancer almost always comes from the gradual growth and enlargement of unexplained nodules in the lungs, therefore, early detection and early diagnosis of the nature of lung nodules is the key to improve the early diagnosis and treatment rate of lung cancer.