Objective To investigate the effectiveness of arthroscopy-assisted combined fixation of Kirschner wire and external fixator for treating extreme distal radial fractures. Methods Between January 2014 and May 2016, 21 patients who suffered from extreme distal radial fractures were treated by arthroscopy-assisted combined fixation of Kirschner wire and external fixator. There were 14 males and 7 females with an age of 32-57 years (mean, 42.3 years). The causes of injury included falling in 13 cases and traffic accident in 8 cases. The fracture type included 8 cases of type 23C1, 9 cases of type 23C2, and 4 cases of type 23C3 according to AO/OTA classification. The time from injury to operation was 3-7 days (mean, 4.4 days). The Mayo score and disability of arm, shoulder, and hand (DASH) score were used to assess the pain and function of the wrist joint. Results There was no needle red swelling, tendon irritation, or orther early complications. All the patients were followed up 10-35 months (mean, 18.3 months). The fracture healing time was 9-13 weeks (mean, 10.6 weeks). At last follow-up, the Mayo score was 87-94 (mean, 90.9); and 17 cases were excellent and 4 were good. The DASH score was 7-13 (mean, 10.6). Conclusion Arthroscopy-assisted combined fixation of Kirschner wire and external fixator for treating extreme distal radial fractures has the advantages of firm fixation, early functional exercise, less postoperative complications, and good functional recovery of wrist joint.