Four and a half year old child always wet his pants for six months may be holding urine, UTI, psychological factors and other factors. 1. habit of holding urine: four and a half year old children are in the active, playful period, easy to habit of holding urine, or forget to pee, thus appearing to pee pants. 2. Urethritis: If a four and a half year old child suffers from urethritis, local inflammatory stimulation may cause the child to have frequent urination, urinary urgency, pain during urination and other symptoms, frequent urination, urinary urgency may cause the child to pee his pants. 3. psychological factors: the child’s mental stress (such as often peeing pants by parents scolding, scolding), major events stimulation and other psychological factors can affect urination habits, affecting the urethra regulation and control ability, resulting in frequent involuntary urination. Four and a half year old child always wet his pants for half a year may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.