[Objective] To explore the characteristics and related management measures of mid-term complications of mobile-bearing medial unicompartmental knee arthroplasty (UKA) . [Methods] A retrospective study was conducted on 313 patients (373 knees) who un- derwent UKA for medial knee osteoarthritis in our department from August 2008 to August 2020. The clinical efficacy was evaluated, while complications in mid-term were analyzed. [Results] All patients were followed up for 12~132 months, with an average of (84.68±12.12) months. The VAS scores decreased significantly (P＜0.05) , whereas the KSS clinical score and functional score, as well as knee flexion range of motion (ROM) significantly increased over time postoperatively (P＜0.05) . Radiographically, there was no significant change in term of the lateral compartment Kellgren-Lawrence classification from the time point preoperatively to the latest follow-up (P＞0.05) . In terms of complications, 22 cases (7.03%) of the 313 patients developed postoperative complications, including 3 males (13.64%) and 19 fe- males (86.36%) . In term of frequency of complications up-down, polyethylene liner dislocation was noted in 12 cases (3.83%) , snapping was in 4 cases (1.28%) , pain was found in 4 cases (1.28%) , aseptic loosening was in 1 case (0.32%) and incision complication was in 1 case (0.32%) . By the time of the latest follow-up, 5 patients (5 knees) , including 4 knees of bearing dislocation and 1 knee of prosthesis loosening, received revision total knee arthroplasty, accounting for 1.34% of the total patients. [Conclusion] The main complication leading to failure of mobile-bearing medial unicompartmental knee arthroplasty is bearing dislocation, which should be paid more attention to.