【Abstract】 Objective To analyze the curative effect of arthroscopic assisted internal fixation and posterolateral approach in the treatment of posterolateral tibial plateau fracture and provide new ideas and methods for clinical treatment of tibial plateau fracture. Methods From January 2015 to June 2019, 64 patients with tibial plateau fractures admitted to our orthopaedic department were selected as the study objects. According to the different surgical plans, they were divided into arthroscopic group and traditional operation group. 31 patients in the arthroscopic group were treated with internal fixation assisted by knee arthroscopy. 33 patients in the traditional operation group were treated with open reduction and internal fixation via posterolateral approach (ORIF). The general baseline data such as gender, age, left and right sides, cause of injury and Schatzker classification, VAS score before operation, 1 day after operation, 1 month after operation and 3 months after operation, HSS score before operation and the last followup after operation and the incidence of postoperative complications were recorded. Results There was no significant difference between the two groups in the general baseline data (P＞0.05). The incision length of the knee arthroscopic group was shorter than that of the traditional operation group (P＜0.05), and the amount of intraoperative bleeding was significantly smaller than that of the traditional operation group (P＜0.05). The operation time of knee arthroscopy group was longer than that of traditional operation group (P＜0.05). The VAS score of knee arthroscopy group was significantly lower than that of traditional operation group on the first day (P＜0.05). There was no significant difference between the first month and the third month (P＞0.05). In the last followup HSS score comparison, the knee arthroscopy group was significantly higher than the traditional operation group (P＜0.05). Conclusion The treatment of posterolateral tibial plateau fracture with knee arthroscopy assisted internal fixation can promote the early rehabilitation of patients with posterolateral tibial plateau fracture, which is in the interests of the patients, and is worthy of further promotion and application.