Under normal circumstances, the human body urinates about 1500ml per day. Urinary output is affected by the external environment and the amount of water consumed, such as when the weather is hot, then the body fluids evaporate too much, which can cause a decrease in the amount of urine; or drink less water to replenish the water is not enough, then the amount of urine may also be moderately reduced. Therefore, normal people every 24 hours urine volume is about 1500ml, if fluctuations are also within the normal range. It is generally recognized that oliguria should not be less than 400 ml or less in 24 hours. If it is less than 400 ml, it suggests that there is a problem with renal filtration and further investigation is needed. Urinary output should not be more than 2500ml, except for drinking water or rehydration, infusion of fluids and other factors, under normal circumstances, if more than 2500ml, it should be considered excessive urination, and further examination is also needed to clarify the cause.