The choice of the site for thoracic closed drainage puncture tube placement depends on the drainage object and the position that the patient can take. For patients with pneumothorax, the site of thoracic puncture tube placement is usually taken at the midline of the second intercostal space on the affected side, and the patient is usually in a semi-recumbent position. This site is chosen because gas tends to collect here in the semi-recumbent position and there are no important blood vessels or organs in this area. The choice of this site can improve the success rate of puncture and placement, ensure the effect of drainage, and reduce the difficulty and risk of puncture. For patients with pleural effusion, if they can take a sitting position, the posterior dorsal ultrasound localization point is usually used for puncture and placement, and for patients who cannot sit or stand, the mid-axillary line of the lateral chest wall and the intercostal area with thin chest wall soft tissue are usually used as the puncture points.