Three-year-old baby pulling pants may be habit did not develop, gastroenteritis and poor development of the anal muscle and other reasons. 1. Habits are not formed: three-year-old babies may have been wearing diapers for the reason that suddenly do not wear diapers, will unconsciously have the urge to urinate or poop do not know to call the parents, thus appearing to pull the pants or peeing pants phenomenon. 2. gastroenteritis: due to three-year-old baby gastrointestinal inflammation, inflammation stimulation of the stomach and intestines will cause diarrhea symptoms, and the baby’s self-control is relatively poor, there may be the case of pulling pants. 3. poor development of the anal muscle: consider the baby because of poor development of the anal muscle, can not independently control defecation, thus causing the baby pulling pants symptoms. When the three-year-old baby appeared to pull pants phenomenon, it is recommended to go to the hospital in time to check the cause of the disease, and cooperate with the doctor for treatment.