Objective To investigate the efficacy of intramedullary nail surgery on the treatment of complex proximal humeral fractures(PHFs).Methods The data of 106 patients with complex PHFs in our hospital(from June 2021 to December 2022)were retrospectively collected and divided into 2 groups according to different surgical protocols.53 patients who underwent intramedullary nailing were classified as group A,and 53 patients who underwent locking plate surgery were classified as group B.The surgical indexes,shoulder joint(abduction and upward)range of motion before and after surgery,Constant-Murley scale,visual analogue scale(VAS)score,bone metabolism[type Ⅰ collagen C-terminal peptide(CTX),osteocalcin(OC),25-hydroxyvitamin D(25-(OH)D)]levels,and incidence of complications were compared between two groups.Results The intraoperative blood loss in group A was lower than that in group B,the incision length,healing time and operation time were shorter than that in group B(P<0.05).The lifting activity and outreaching activity of group A were higher than those of group B 1 and 3 months after operation(P<0.05).The Constant-Murley score of group A was higher than that of group B 1 month and 3 months after surgery,and the VAS score was lower than that of group B(P<0.05).Serum CTX levels in group A were lower than those in group B 1 and 3 months after surgery,and serum OC and 25-(OH)D levels were higher than those in groupB(P<0.05).The incidence of complications in group A was 1.89%(1/53)lower than that in group B 16.98%(9/53)(P<0.05).Conclusion Compared with locking plate surgery for patients with complex PHFs,intramedullary napping is more helpful to optimize surgical indicators,improve shoulder joint function and mobility,reduce postoperative pain,improve bone metabolism,promote fracture healing,and reduce complications.