The cerebellar vermis is a normal anatomical structure found in the human body. Some patients may have congenital developmental malformations that result in cerebellar vermis absence, which can be detected on examination. In some patients, cerebellar vermis is a neurological abnormality that can have a serious impact on mental retardation, ataxia, and balance disorders. Cerebellar hypoplasia is a congenital developmental abnormality, which is more common in newborns and late pregnancy, and cannot be treated with current clinical techniques. In some severe cases, it may affect the brain function and leave the above mentioned sequelae. If cerebellar earthworm defects are detected during pregnancy checkups, it is recommended to consult a doctor and make reasonable treatment under the doctor’s guidance.