Objective To reconstruct complex fracture models using 3D printing technique and explore the role of 3D printing technique in treating proximal humeral fractures.Methods Fifty patients with complex proximal humeral fractures admitted from June 2015 to June 2017 were enrolled in this study,and were randomly divided into two groups.The patients in group A received conventional treatment,while the patients in group B received adjuvant therapy that complex fractures were reconstructed using 3D printing techniques in addition to conventional treatment.The clinical indicators of surgery duration,blood loss volume during surgery,fracture healing time,and the number of C-arm fluoroscopy during surgery were compared between the two groups.The Neer Shoulder Scale (Neer score) and the CMS shoulder scoring system (CMS score) were used before and 12 months after the surgery to evaluate the shoulder function of the patients.Results After the surgery,the clinical indicators of group B were better than those of group A (P<0.05).The Neer score and CMS score of the two groups were both improved after 12 months of follow-up.The scores of the patients in group B were better than those in group A,and the differences were statistically significant (P<0.05).Conclusion 3D printing technique makes it possible to perform simulation surgery before real surgery,and present surgical procedures to physicians in advance and more intuitively.Applying the technique to the treatment of complex proximal humeral fractures can not only reduce operation time,bleeding volume during operation,and healing time,but also restore shoulder joint functions more effectively,greatly improving the quality of surgery,which deserves further applicaiton to fracture repair.