1, the infant’s head is abnormally enlarged, the fontanelle is full and bulging, repeated vomiting and crying, the cranial percussion shows “broken can sound”, and both eyes show “sunset sign”. 2.Cranial X-ray examination shows that the cranial cavity is enlarged, the skull is thinned, the cranial suture is widened, and the fontanelle is enlarged. 3. Ultrasound examination of the brain shows symmetrical enlargement of bilateral ventricles. 4.CT or MRI examination of the head can show the degree of ventricular enlargement and can measure the thickness of the cortex to know the site of obstruction and the cause of hydrocephalus. 5.Some of the basic tests may be used repeatedly during the treatment process. Early prenatal diagnosis of children with hydrocephalus is an important way to prevent the birth of children with hydrocephalus. Since obvious hydrocephalus can be detected by ultrasound at 12 – 18 weeks of gestation, it is important to strengthen the use of ultrasound in prenatal diagnosis, to terminate pregnancy early, to prevent the birth of children with hydrocephalus, and to reduce the birth rate of congenital hydrocephalus.