[Objective] To introduce the surgical technique and clinical efficacy of F3 mini-locking plate for ankle fractures combined with posteromedial fragment..[Methods] From February 2019 to February 2021,12 patients with posteromedial fragment were underwent surgical treatment in our hospital. Surgical time was determined from 1 to 10 days after injury. Surgical exposure was adopted among anterior and posterior window between tibialis posterior and neurovascular bundle through posteromedial approach. Following reduction and screw or tension band fixation of the anterior collicular fragment, posteromedial and posterior collicular fragment was fixed overall by F3 mini-locking plate. [Results] There was no intraoperative neurovascular injury, no incision infection and flap necrosis. No cases with posterior tibialis tendon irritation and implant failure, loss of fracture reduction as well as joint incongruity were observed at the last follow-up . AOFAS ankle-hind foot score was 86 to 96. [Conclusion] The fixation of posteromedial fragment with F3 mini- locking plate can achieve effective stability, reduce implant-related complications, and facilitate the recovery of ankle function, which is a feasible surgical scheme.