[Objective]To Probe the causes of significant operatiive complications of ossification of posterior longitudinal ligament as well as the treatment outcomes in order to reduce the surgical morbidities and to suggest preventive measures of complications.[Method]The surgical data of 85 cases with ossification of posterior longitudinal ligament were reviewed form March 2002 to May 2006.In continuous long segment OPLL which were treated by bilaminectomy with internal fixation system;short segment OPLL which were treated by corpectomy of anterior cervical approach with bone of autograft and anterior cervical spine locking plates.[Result]Totally 66 cases were followed-up from 3 to 25 months with an average of 13 months.Complication of posteior cervical approach:8 cases with the pain of neck-shoulder,which resulted from postoperative radiculopathy and nerve root irritation or injury.Most of 8 cases were recovered in 2 to 20 weeks by conservative treatment such as antalgica,dehydration and physiotherapy.Four cases with quadriparesis or symptom deteriorate,which resulted from reperfusion injury of spine cord.Two cases were recovered by hyperbaric oxygen and medication and 1 cases recovered not enough.Two cases with posterior cervical hemotoma were caused by bleeding of smaller blood vessels and obstruction of drainage.One case of CSF leakage were cured in 3 days with cervical spinal immobilization and moderate local compressiom.Two cases of local infection were cured during 20 days with antibiotics or combined with debridement and suturing.Complications of anterior cervical approach:a cases with quadriparesis or symptom deteriorate;1 case of CSF leakage.Complications related to instruments included 1 case of titanium net subsidence and 1 case of single lateral mass screw back-out.[Conclusion]Many kinds of operative complications could occur in either anterior or posterior approach of surgery of ossification of posterior longitudinal ligament.Preoperative good preparation,intraoperative carefull operation and postoperative strengthened management are the key points to decrease and prevent operative related complications.