OBJECTIVES: This study aims to assess the predictive value of preoperative parameters on recovery outcomes in patients with myelopathy caused by cervical ossification of the posterior longitudinal ligament (COPLL) undergoing laminoplasty (LAMP). METHODS: A retrospective analysis was performed on myelopathy patients caused by COPLL who underwent LAMP between 2017 and 2020. Preoperative variables, including basic epidemiological characteristics, comorbidities, functional scores, K-line-related parameters, Torg-Pavlov ratio, maximal SCOR and COPLL shape, were analyzed for their predictive influence on postoperative outcomes in cervical spine function, upper and lower extremity function, bladder function, and quality of life (QOL). Binary logistic regression model analyses were used to evaluate predictive accuracy. RESULTS: A total of 84 patients were included in the study. Preoperative parameters were significant predictors of postoperative improvement following LAMP surgery for myelopathy caused by COPLL. K-line-related factors, including K-line (-) (AUC = 0.80) and K-line on sagittal T1WI (-) (AUC = 0.76), were important predictors of cervical spine function improvement. Preoperative QOL scores (AUC = 0.78) also played a significant role in predicting cervical spine function improvement. For upper extremity function, preoperative upper extremity scores were a key predictor (AUC = 0.79), while C4-C6 K-line (-) (AUC = 0.81) was also a relevant factor. Similarly, preoperative lower extremity scores were crucial for predicting lower extremity function improvement (AUC = 0.85), and preoperative QOL scores were significant predictors of QOL improvement (AUC = 0.78). Other parameters, such as the Torg-Pavlov ratio, maximal SCOR, and the shape of COPLL, provided supplementary predictive value, though their influence was secondary to JOACMEQ scores and K-line parameters. Bladder function showed minimal postoperative improvement, with preoperative bladder status and the Torg-Pavlov ratio at C5 being the primary predictors for bladder improvement. Overall, preoperative K-line findings, JOACMEQ scores, and spinal canal measurements provided valuable guidance for postoperative expectations and surgical planning. CONCLUSIONS: Preoperative K-line parameters and JOACMEQ scores are robust predictors of functional recovery in myelopathy patients caused by COPLL undergoing LAMP. While Torg-Pavlov ratio, maximal SCOR, and the shape of COPLL offer additional predictive value for overall recovery, they remain useful for preoperative surgical planning. These findings emphasize the importance of comprehensive preoperative assessment to optimize outcomes.