Mouth is very dry drink water are not thirst may be due to mental thirst, diabetes, dry syndrome, etc., need to be specifically analyzed. 1. Psychogenic thirst syndrome: patients suffering from psychogenic thirst syndrome due to long-term large amounts of water leading to the body’s antidiuretic hormone secretion is inhibited, which leads to even if the mouth is very dry and drink water do not quench the thirst of the situation. 2. Diabetes: diabetic patients due to increased blood glucose leads to a large amount of water in the body with the urinary discharge, resulting in dry lips. Diabetic patients in addition to a very dry mouth and drink water do not quench the thirst of the situation, but also can appear more food, more urine, weight loss and other symptoms. 3. Dry syndrome: Dry syndrome is a chronic inflammatory autoimmune disease involving exocrine glands, patients can have dry mouth and drink water without quenching their thirst as the main symptom, accompanied by other symptoms such as dry eyes. Once a patient finds himself dry mouth and drinking water does not quench his thirst, he needs to consult a doctor in a timely manner, under the guidance of the doctor to improve the relevant examination, and take targeted measures.