Drinking a lot of water and urinating less, may be physiological regulation, may also be pathological changes.1, normal people if in a dehydrated condition, the water consumed will only replenish the water in the blood vessels, and will not be immediately metabolized to produce urine volume. When the amount of drinking water reaches a certain saturation state, only when the amount of urine will appear. Usually, as long as the urine volume is greater than 400ml per day, it is not considered to be pathologically significant oliguria. If the urine volume is less than 400ml per day, it is considered to be pathological oliguria caused by various diseases; 2, oliguria caused by renal metabolism abnormality, commonly found in patients with renal insufficiency, renal failure, uremia patients. At this time due to glomerular damage caused by the decline in filtration capacity, there will be a lot of drinking water and water can not be metabolized through the kidneys to produce urine out of the body. In the long run, the patient will have edema, and the urine output decreases progressively. In the pathological state, a daily urine output of less than 400 ml is called oliguria. A daily urine output of less than 100 ml is called anuria. If there is a combination of such conditions, immediate medical attention is required for further consultation and treatment.