Surgical treatment usually adopts suboccipital median approach. During the operation, the posterior edge of the foramen magnum was exposed, and the lamina of atlas, axis, neck 3-5 and spinous process were exposed. Part of the bone at the posterior edge of the foramen magnum and the lamina and spinous process of cervical vertebra 1-2 were bitten off, exposing the dura mater. Open the arachnoid membrane on the surface of spinal cord, and retract the lower edge of cerebellar tonsil of hernia above the posterior edge of foramen magnum with electrotome. Cotex artificial dura mater is used to reduce tension and suture dura mater. Nail neck 2-4 lateral mass, occipital neck fusion internal fixation system, usually at the angle of 105, fixed with screws. After fixation, the epidural drainage tube was retained and sutured layer by layer. Patients wear neck brace for 4-8 weeks after operation.