Leakage of urine in four-year-old children may be caused by physiological factors, acute urinary tract infection disease, neurogenic bladder and other factors. 1. Physiological factors: under normal circumstances, some four-year-olds may experience physiological leakage of urine on a daily basis, especially when playing excessively, but it will not occur frequently and may return to normal after the age of five. 2. Acute urinary tract infections: children do not pay attention to the hygiene of the lower body, may be induced by acute urinary tract infections, such as acute cystitis, resulting in hypersensitivity of the bladder mucosa, which can lead to urge urinary incontinence, which can lead to urinary leakage, accompanied by urinary pain, urinary frequency, urinary urgency and other symptoms. 3. Neurogenic bladder: may be related to a variety of factors, such as infectious factors, traumatic factors, resulting in damage to the nerves innervating the bladder, will make the four-year-old child frequent urinary leakage, may also be difficult to urinate, as well as urinary retention and other abnormal manifestations. Frequent leakage of urine and other abnormalities in four-year-olds should be recognized as a disease, and parents are advised to take their children to the doctor for examination and treatment.