Abstract: Objective To explore the short-term and long-term efficacy of anterior cervical discectomy and fusion (ACDF) under microscopic assistance for patients with focal ossification of the posterior longitudinal ligament (OPLL). Methods A total of 105 patients with focal OPLL treated between February 2020 and February 2022 were retrospectively selected. They were divided into microscope group (n=56) and conventional group (n=49) based on whether ACDF was assisted by microscopy. Perioperative indicators, Visual Analogue Scale (VAS) scores, 36-item Short-Form Health Survey (SF-36) scores, spinal canal cross-sectional area at the narrowest point, anteroposterior diameter of the spinal cord, cervical range of motion, intervertebral height, joint functionJapanese Orthopaedic Association (JOA) cervical spine disease score and Neck Disability Index (NDI), and occurrence of complication were observed. Results The average operative time and average hospital stay in the microscope group were shorter than those in the conventional group(141.85±18.35) min and (10.18±1.58) d versus (159.46±21.42) min and (12.03±1.82) d, P<0.05. The average intraoperative blood loss in the microscope group was (80.65±7.28) mL, which was less than that (103.52±10.43) mL in the conventional group (P<0.05). The VAS score and SF-36 score at six months postoperatively were better in the microscope group compared to the conventional group (2.82±0.53) and (79.56±5.68) versus (3.51±0.60) and (72.35±4.77), respectively, P<0.05. Spinal canal area and anteroposterior diameter of the spinal cord between the two groups postoperatively showed statistically significant differences (138.24±24.32) mm versus (123.62±18.74) mm, (5.42±0.46) mm versus (4.73±0.51) mm, P<0.05. The cervical range of motion at six months postoperatively in the microscope group showed significant difference compared with that in the conventional group(25.21±3.37) °versus (28.65±3.56) °, P<0.05. The complication rate in the microscope group was lower than that in the conventional group (5.36% versus 18.37%, P<0.05). Japanese orthopaedic association (JOA) and National Death Index (NDI) scores showed statistically significant between-group and time-point difference (P<0.05). Conclusion Microscopic assistance during ACDF for focal OPLL provides a clear field of vision and facilitates effective decompression of the spinal cord by using a drill to remove and thin the ossified focus, thereby improving short-term pain and joint function while reducing the risk of spinal cord injury and other complications.