Sixteen cases of cervical spinal cord injury with developmental stenosis of cervical spinal canal were treated. The numbness and quadriplegia of the patients were caused by hyperextension X-ray of the cervical spine showed no fracture or dislocation but the sagittal diameter of the canal and that of the corresponding cervical vertebral body was less than 0.75. All of the patients were treated by operation including laminoplasty on 12 cases. The numbness and quadriplegia in most of the patients were improved obviously after operation. The mechanism of hyperextension injury on the cervical spinal cord was discussed. When spinal column was extended, annulus fibrosus of disk and ligamentum flavum would enfold into the spinal canal and only a slight force would do severe on the cord. Laminoplasty is the recommended treatment for this kind of lesions.