Normal renal function but less urine may be physiological reasons, may also be pathological reasons, it is recommended to go to the hospital for examination to clarify the diagnosis and then targeted treatment. When drinking less water or evaporating more sweat and skin due to the hot weather, it may lead to a decrease in urine output. At this time belongs to physiological oliguria, only need to appropriate hydration can be. Some lesions outside the kidneys can also lead to decreased urine output. When the urinary system is infected, it will produce the symptoms of less urine, frequent urination and painful urination. Urinary stones including ureteral stones and bladder stones may also lead to decreased urination. It is important to note that oliguria is defined as a urine output of less than 400 ml in 24 h. Sometimes the artificial sensation of less urine does not reach the clinical meaning of oliguria. On the basis of the correct judgment, it is recommended to go to the hospital for examination, clear diagnosis, and then follow the doctor’s instructions for appropriate treatment.