Chiari malformation is a condition in which the cerebellar tonsils herniate into the spinal canal and the medulla oblongata and part of the fourth ventricle also herniate into the spinal canal, also known as “submural herniation of the cerebellar tonsils”. It is often associated with compression of adjacent cranial and cervical nerves, hydrocephalus and spinal cavity formation. Due to the herniation of the inferior cerebellar tonsils, the cranial and cervical nerves are compressed, causing neck pain and restricted movement, hoarseness, and difficulty in swallowing. Due to compression of the medulla oblongata and the upper cervical segment of the spinal cord, there may be limb movement disorders, hemiparesis and quadriplegia, sensory disorders of the extremities, hyperactive tendon reflexes, pathological reflexes, and urinary and fecal disorders. If a cavity is formed in the spinal cord, abnormal sensation, hyperalgesia or loss of pain and temperature sensation, muscle atrophy of both upper limbs, weakness, muscle atrophy of both hands, and “claw-shaped hands” may occur. If the cerebellum is compressed, there may be unstable walking and nystagmus. In case of hydrocephalus, headache, vomiting and other symptoms of increased intracranial pressure may occur. The best test is MRI, which can clearly show the exact location of the subungual herniation, the presence of medulla oblongata and subventricular herniation, the displacement of the brainstem, the presence of spinal cord cavity and hydrocephalus. Surgery is the main treatment for this disease and is a routine procedure in our department. Surgery is performed to remove the occipital bone and/or vertebrae that are compressing the brain, spinal cord and other neural tissues, and if necessary, to cut open part of the dura mater and dura spinalis to relieve the compression. Some patients who still have hydrocephalus often require ventriculo-abdominal shunts.