CO2 freezing is a method of destroying abnormal living tissues using ultra-low temperature. According to the Joule-Thomson principle, high-pressure CO2 gas is released through small holes and throttled to expand refrigeration to produce low temperatures as low as -80°C, which forms a certain size of ice ball in the anterior part of the cryoprobe and can effectively kill tumors. Cryopreservation is performed with a cryoprobe in the working channel of the tracheoscope. The end of the cryoprobe can act directly on the tumor area to form an ice ball of about 15 mm, which can be divided into freeze-cut and freeze-thaw according to different purposes. As shown in the figure, the left main endobronchial tuberculosis with airway stenosis, 3 months after stent placement, the tuberculous granuloma grew out of the stent mesh again, and the granuloma was removed by freezing, and at the same time the base of the stent was treated with freezing to prevent the granuloma from forming again. Granuloma grows on the surface of the stent Remove the granuloma by freezing After six months, the lumen is enlarged, remove the endoprosthesis, and the trauma is treated with freezing again For diffuse or caseous tuberculosis in the airway, a combination of APC and freezing technology can be used, which can quickly destroy tubercle bacilli in the airway and keep the airway open, which can prevent airway stenosis and prevent the need for placing an endoprosthesis.