Abstract:[Objective] To investigate the clinical effect of ultrasound-guided closed reduction and fixation with modified mini-exter- nal fixator for unstable distal radius fractures in children. [Methods] From March 2017 to December 2020, 55 children with unstable frac- tures of the distal radius were enrolled in this study. According to doctor-patient communication results, 29 patients were treated with ultra- sound-guided closed reduction and fixation with modified mini-external fixator (the ultrasound group) , while the remaining 26 children were treated with traditional external fixator under fluoroscopy (the fluoroscopy group) . The perioperative, follow-up and imaging data were compared between the two groups. [Results] All the patients in both groups had operation performed smoothly. The ultrasound group proved significantly superior to the fluoroscopy group in terms of operation time, imaging exposure times, intraoperative blood loss and hospital stay (P<0.05) . In addition, the WB-faces pain scores in the ultrasound group were significantly lower than those in the fluoroscopy group at 1day and 3 days postoperatively (P<0.05) . All patients in both groups were followed up for (18.53±4.24) months on average, with no signifi- cant differences in the time to remove external fixator and the time to resume full weight-bearing activity between the two groups (P>0.05) . Compared with those 3 months after surgery, the extension-flexion range of motion (ROM) and ulnar -radial deviation ROM significantly in- creased in both groups (P<0.05) , the Gartland-Werlay scores also improved in both groups at the last follow-up whereas without statistical- ly significant differences (P>0.05) . However, there were no significant differences in the abovesaid indexes between the two groups at any corresponding time points (P>0.05) . Radiographically, there was no significant difference in fracture reduction quality between the two groups (P>0.05) . The PT, RI and RL in both groups were significantly improved after operation (P<0.05) , whereas no significant differenc- es in the above imaging parameters were noticed between the two groups at corresponding time points (P>0.05) . [Conclusion] The ultra- sound-guided closed reduction and fixation with modified mini-external fixator does achieve considerably better clinical outcomes over the fluoroscopic closed reduction and conventional external fixator for distal radial unstable fractures in children.