Objective: To evaluate the effect of unilateral external fixation in the treatment of fresh Monteggia fractures in children. Methods: A total of 16 children with fresh Monteggia fractures were enrolled in this study, who underwent unilateral external fixation, intraoperative fracture reduction, arthrography to evaluate the reduction effect, and postoperative forearm plaster fixation in supination position. Results: All patients had surgical procedures performed smoothly without serious complications. All 16 children were followed up for 6-18 months. At the last follow-up, the range of elbow flexion and extension and the forearm rotation were restored well. Compared with 6 weeks after the operation, the range of elbow flexion and extension was significantly increased (P<0.05), and the range of forearm rotation was significantly increased (P< 0.05). According to Mackay's curative effect evaluation standard and postoperative images, both of the excellent rate of surgery effect and fracture reduction quality was 100%. Compared with 6 weeks after operation, the fractures of all cases were healed at the last follow-up, and the difference was statistically significant (P<0.05). There was no significant difference between control and case group about brachioradial joint alignment and normal ulnar force lines (P>0.05). Conclusion: For fresh children's Monteggia fractures, the fracture types are ulnar shaft long oblique and comminuted fractures, unilateral external fixation is an effective treatment method, which is simple to operate and less traumatic, and is worthy of promotion.