Abstract： Objective:To investigate the therapeutic effect of Multiloc intramedullary nail and steel plate fixation in the treatment of humeral shaft fractures.Methods:60 patients of humeral shaft fractures who were treated in department of orthopedics were divided into steel plate group(30 cases,treated with internal fixation with locking plate)and intramedullary nail group(30 cases,treated with Multiloc intramedullary nail).The operation indexes,shoulder joint range of motion 3 and 6 months after operation and shoulder joint and elbow joint function 1 year after operation were compared between the two groups,and the complications were recorded.Results:Compared with the steel plate group,the length of incision in the intramedullary nail group reduced,the amount of intraoperative bleeding reduced,the time of operation shortened(P＜0.05).Compared with preoperative,the range of motion of shoulder joint flexion and abduction and lifting at 3 and 6 months after operation was significantly greater than those before operation in the two groups,and the intramedullary nail group was greater than that in the steel plate group(P＜0.05).The scores of Neer shoulder joint function and Mayo elbow joint function 1 year after operation in both groups were significantly higher than those before operation(P＜0.05),but there was no significant difference between the two groups(P＞0.05).The total complication rate in the intramedullary nail group was lower than that in the steel plate group(6.67％vs 26.67％,P＜0.05).Conclusion:Both internal fixation with locking plate and Multiloc intramedullary nail can effectively treat the comminuted fracture of humeral shaft,promote the reduction of the fracture end,improve the shoulder joint and elbow joint function.However,Multiloc humeral intramedullary nail can effectively shorten the operation time,reduce the intraoperative bleeding volume and the risk of postoperative complications,promote the improvement of shoulder joint range of motion after operation.