Objective To analyze the effect of cervical.curvature and intervertebral height on the surgical outcome of posterior decompression in patients with multi-level cervical spondylotic myelopathy.Method A total of 50 patients with multi-segment cervical spondylotic myelopathy (≥ 3 segments),treated with posterior decompression from June 2006 to January 2009 were retrospectively analyzed.Twenty six patients underwent cervical omni-posterior decompression and lateral mass screw internal fixation (group A); 24patients underwent expansive open-door laminoplasty (group B).The effects of changing of cervical curvature and intervertebral height on JOA score and VAS score were analyzed.Results All patients were followed up for 8 months to 4 years (average,24 ±5.5 months).There were statistical differences of cervical curvature angles between preoperative and 3 days postoperatively in group A,while no statistical differences in group B.There were no statistical differences of cervical curvature angles between 3 days,6 months and 3 years postoperatively in group A,while there were differences in group B After further analysis of the loss of cervical curvature and intervertebral height,the result showed that JOA score and VAS score in the low-loss group were better than those in the high-loss group.Conclusion Lateral mass screw internal fixation after cervical omni-posterior decompression had many advantages such as reducing the change of cervical curvature,the loss of intervertebral height and incidence of cervical axial symptoms.