[Objective] To investigate the surgical technology and clinical efficacy of using the arthroscopic treatment of intra-articular displaced posterior malleolus fracture. [Methods] A total of 31 patients were treated with posterior approaches of arthroscopically assisted reduction for posterior malleolus fractures and fixed with hollow screws in our hospital from Septembe 2019 to September 2022. The perioperative, follow-up and radiographic documents were analysed. [Results] Thirty-one cases of patients were recorded. The mean follow?up period ranged from 12 to 31 months, mean (13.6±3.4) months. All incisions healed in one stage without postoperative complications such as nerve and vessel injury. Postoperatively X?ray showed complete fracture healing time was from 8 to 14 weeks, with an average of 9.4±2.3 weeks. The visual analogue scale （VAS） scores decreased significantly (P<0.05) , American orthopaedic foot & ankle society（AOFAS）score increased from (38.2±11.7) to (97.4±5.8) and Maryland score increased from (52.7±17.1) to (95.5±6.3) after the operation, the differences were all significant (P<0.05) . Postoperative X-ray or CT showed the articular surface smooth or steps less than 1 mm in 28 patients, 3 cases of patients with joints steps less than 2 mm. [Conclusions] The arthroscopic treatment of the intra?articular displaced posterior malleolus fracture is an effective and precise method, with shorter fracture healing time, good clinical efficacy, less soft tissue injury and minimally postoperative complications.