In infants, care should be taken to differentiate from the following: 1. immature children: the head enlarges more rapidly, some resembling hydrocephalus, but the ventricles are not large. 2, rickets: head enlargement is mostly square and has other symptoms of rickets. 3.Dysmorphic large head: the head is large and growing fast, with obvious mental deficiency, no droopy eyes, and normal ventriculography. 4, chronic subdural hematoma, the head enlarges more slowly, more red or yellow fluid is visible in the subdural penetration, there is bleeding in the fundus, CT can confirm the diagnosis. 5, intracranial occupying lesions such as tumors, abscesses, etc. In the elderly, hydrocephalus also needs to be distinguished from enlargement of the relative ventricular system due to brain atrophy. The two can be differentiated from symptoms and imaging examinations. In pure atrophy, there are no typical symptoms of hydrocephalus, such as dementia, urinary incontinence and unsteady gait, and in CT and MRI, the ventricular system is enlarged and the sulcus is widened, but crucially, there is no periventricular edema. The clinical findings are not consistent and are related to the age at which the pathological changes appear, the severity of the pathology, and the duration of the disease. Congenital hydrocephalus in the fetus mostly results in stillbirth, and hydrocephalus may appear at any age after birth, mostly in the first 6 months of life. In younger patients, the cranial sutures are not joined and the head is easily enlarged, so there are fewer symptoms of increased intracranial pressure. Hydrocephalus manifests itself primarily as a rapid, progressive enlargement of the infant’s head weeks or months after birth. In normal infants, the head circumference increases by 1.2-1.3 cm per month in the earliest six months, but in this case, it is 2-3 times larger, with a round skull, frontal protrusion, abnormal enlargement of the fornix, enlarged and bulging fontanelle, separation of the cranial suture, thinning of the skull and even transparency, and the “broken pot sound” (Maceen) sign on percussion. The temporal frontal area shows angry veins, the eyes are downwardly rotated, and the upper sclera is often exposed (sunset sign). The infant is depressed and cannot lift the head. In severe cases, there may be brain dysfunction, including epilepsy, visual and olfactory impairment, nystagmus, strabismus, limb paralysis, and mental retardation. Because of the compensatory enlargement of the infant’s head, headache, vomiting, and optic nerve papillomegaly are not obvious.