Objective to investigate the clinical effect of multiloc intramedullary nail in the treatment of adult three part proximal humeral fractures. Methods from April 2017 to April 2019, a total of 20 patients with this kind of disease were treated in our hospital. All the patients were treated with lateral acromion longitudinal incision and implanted with multiloc intramedullary nail. Neer shoulder function score system was used to evaluate the shoulder joint function and postoperative curative effect. Results all 20 patients were followed up for 12-36 months with an average of 20.5 months. According to neer shoulder function score system, 15 cases were excellent, 4 cases were good and 1 case was fair. The excellent and good rate was 95%; the score was 71-94, with an average of 84.5. Conclusion neer IV fractures of proximal humerus in adults are intra-articular fractures and need early surgical treatment. Through limited incision and multiloc intramedullary nail fixation, good clinical effect was achieved.