Thirst after lung nodule surgery is considered to be caused by routine medication before surgery, prolonged open-mouth breathing during surgery, and anesthetic drugs. 1. Routine medication before surgery: atropine or scopolamine, which is a typical M cholinergic receptor blocker, inhibits the glands, especially the salivary glands, resulting in dry mouth and other adverse reactions, leading to postoperative thirst. 2. Prolonged open-mouth breathing during surgery: water or food fasting before surgery, if there is tracheal intubation for general anesthesia, patients will be forced to open their mouths for a long time during intubation, and dry gases coming in and out of the respiratory tract will lead to postoperative thirst. 3. Anesthesia drugs: physiological changes caused by anesthesia drugs during surgery should not be ignored. Combined anesthesia can cause corresponding sympathetic nerve blockade, causing relative vasodilatation and thirst due to low blood volume. In addition, blood loss during lung nodule surgery, inappropriate temperature and humidity of the ward environment, and patients’ poor tolerance to thirst are all direct causes of thirst.