Lung fluid refers to pleural effusion, and lung fluid extraction generally refers to pleural puncture, referred to as thoracocentesis. The fluid extracted by thoracocentesis can diagnose and treat the disease, but if it is not operated properly, it can cause certain “side effects”, that is to say, it may cause complications, which may result in pneumothorax, pleural reaction, and intrathoracic infection, etc. Pneumothorax: if the lung is damaged during the puncture or if the pleura is mistakenly punctured, it may result in the occurrence of pneumothorax. 1. Pneumothorax: Pneumothorax can occur if the lungs are damaged during puncture or if the pleura is mistakenly punctured in the visceral layer. 2. Pleural reaction: In the process of chest puncture, if the patient is overly nervous or the speed of fluid extraction is too fast, pleural reaction such as dizziness, sweating and palpitation will easily occur. 3. Intrathoracic infection: If strict sterilization is not carried out in the process of chest puncture, it is easy to lead to the invasion of bacteria causing intrathoracic infection. In addition, pumping too much fluid at one time may also lead to compound pulmonary edema. Chest puncture must be operated by professional doctors and have strict indications and contraindications.