Generally if a person is able to completely discharge the amount of urine in the bladder when urinating, the amount of residual urine in the bladder is 0. However, a residual urine in the bladder of less than 50 ml is normal, and most people have a residual urine volume of less than 20 ml. If the amount of residual urine in the bladder is greater than 50 ml, it is known as an increase in the amount of residual urine. If the amount of residual urine in the bladder is too much, it may be the bladder discharge obstruction occurs, there may be frequent urination, urinary urgency and other symptoms, may cause infection, stone formation, etc., the amount of residual urine will lead to a large number of bacterial reproduction in the bladder, which may cause recurrent inflammatory lesions of the bladder, we should go to the hospital in a timely manner to the symptomatic treatment. Drink more water in daily life, urinate regularly, eat more fresh fruits and vegetables in daily life, and eat less spicy and irritating food to avoid irritating the bladder. If there is any discomfort, consult a doctor in time.