Objective To investigate the efficacy of external pelvic reduction frame system combined with tunnel screw fixation in the treatment of Tile C1 pelvic fracture.Methods A retrospective case series analysis of 15 patients with Tile C1 pelvic fractures from January 2014 to October 2016 was pedormed.Clinical data included seven males and eight females,aged 26-84 years (mean,48.9 years).According to Tile classification,there were five cases of type C1.1,three cases of C1.2,and seven cases of type C1.3.The average time from injury to surgery was 9.5 days (range,4-33 days).All patients received the treatment of external pelvic reduction frame system combined with tunnel screw fixation.The operation time,intraoperative blood loss,and complications were recorded.The fracture reduction quality was evaluated according to the Matta criteria,and the clinical function and neurological function were evaluated by the Majeed functional scoring system and the Gibbons sacral nerve injury grading,respectively.Results The patients were followed up for an average of 16 months (range,12-24 months).The mean operation time was 139 minutes (range,50-250 minutes),and the mean intraoperative blood loss was 90 ml (range,20-260 ml).No complications such as wound infection,loose internal fixation,rupture or loss of reduction occurred in the patients.According to the Matta score,14 patients obtained anatomical reduction,and one obtained satisfactory reduction.At the last follow-up,according to the Majeed functional scoring criteria,the results were excellent in all 15 patients,with an excellent and good rate of 100％.According to Gibbons sacral nerve injury grading,two out of the three patients with neurologic impairment before the operation recovered completely while the remaining one did not recover.Conclusion In the treatment of Tile C 1 pelvic fractures,external pelvic frame reduction system combined with tunnel screw fixation can attain satisfactory fracture reduction,reliable fixation,and good functional recovery.