Methods: This study is a randomized clinical trial with randomized, controlled, multicenter research design. The OPLL patients will be randomly assigned in one of the two treatment groups: ACAF surgery and ACCF surgery. Five outcome measures will be collected pre-operative for baseline, and then at1, 12, 24, 48, 96,240weeks post-operative follow-up visits, including : (1) Japanese Orthopaedic Association (JOA) scales to assess the spinal cord functions.(2)Visual analogue scale (VAS) to assess pain relief. (3)NURIC Graded to assess walking function.(4) Neck Disabilitv Index(NDI) to assess cervical function . (5) radiological parameters to assess ossification forward distance. And the pre & postoperative radiological parameters, and surgical complications were also investigated. The investigator performing the outcome measures will be blinded to group assignment, and therefore will not participate in treatment. After randomization, the ACAF group will receive anterior controllable antedisplacement and fusion and the ACCF group will receive anterior cervical corpectomy decompression and fusion.