For patients of thoracolumbar kyphosis with ankylosing spondylitis ( AS ), it is significant to reconstruct the sagittal balance and the chin-brow vertical angle by spinal osteotomy. Relocation of the center of gravity to pelvic neutral positional line is the key to reconstruct sagittal balance. In addition, chin-brow vertical angle is also important for patients with cervical ankylosis. Better outcomes depend on the selection of optimal osteotomy level.