Two and a half year old babies fontanel not closed may be due to rickets, hydrocephalus and hypothyroidism, etc., according to the cause of the targeted treatment, including calcium supplementation, correction of primary diseases and other treatments. When a newborn is born, the fontanel is not closed, with the growth of the skull, gradually ossified and become smaller, the normal fontanel will be closed at about one and a half years old. Normal two and a half year old baby at this time the fontanel has closed completely, not closed may be due to rickets, hydrocephalus or hypothyroidism and so on. Rickets can be improved by supplementing vitamin D and calcium, and adhering to the sun to improve, hydrocephalus caused by fontanel not closed can be improved by brain surgery to reduce intracranial pressure, hypothyroidism can be prescribed by thyroid hormone supplementation to treat. The two and a half year old baby fontanel did not close the fontanel need to consult the diagnosis, according to the cause of the timely targeted treatment.