Abstract:[Objective] To evaluate the efficacy of valgus osteotomy for the treatment of Pauwels type III old femoral neck fracture in children. [Methods] From 2016 to 2021, 4 patients with Pauwels TYPE III old femoral neck fracture were treated with valgus osteotomy of proximal femur with internal fixation by locking compression pediatric hip plate (LCP-PHP) . The clinical and imaging documents were summarized. [Results] All the 4 patients were successfully operated on with operation time of (161.25 ± 51.05) min, incision length of (10.75±2.98) cm, intraoperative blood loss of (192.50±86.94) ml, and primary healing of the incision. All patients had unilateral spica cast as external fixation for 6 weeks after surgery. The patients resumed actively affected limb motion without weight bearing one month after the cast removed, and then full weight-bearing activity 3 months later. All the patients were followed up for 9~23 months, with an average of (18.50±6.45) months. During the follow-up, there was no reinjury or revision surgery in anyone of them. The VAS score significantly de- creased (P<0.05) , while Harris score and hip flexion-extension range of motion (ROM) significantly increased at the latest follow up com- pared with those preoperatively (P<0.05) . At the latest follow up, all the 4 patients recovered normal walking without obvious claudication, whereas with normal squatting activities, and resumed normal daily life activity and sports capacity. [Conclusion] Valgus osteotomy is an ef- fective treatment for old femoral neck fracture in children.