Objective: To study the clinical outcomes and characteristics of fracture healing of a modified internal fixation method, which was implemented by placing four and two screws respectively at the proximal and distal end of the locking plate in the minimally invasive percutaneous plate osteosynthesis (MIPPO) for patients with proximal humeral fractures.Methods: Patients in Peking University Third Hospital from February 2010 to December 2016 were brought into this retrospective study. Based on different operation methods, they were divided into minimally invasive (MI) group and non-minimally invasive (non-MI) group, and the patients in MI group were performed with the modified internal fixation. In order to observe the varying efficacy for different fracture types between the two groups, we further investigated the patients with Neer two-part and three-part fracture, respectively. The follow-up parameters included general physical examination, X-ray, visual analogue scale (VAS) and Constant-Murley score.Results: A total of 117 patients with an average age of (61.5±16.2) years met the inclusion criteria, and MI group included 45 patients, non-MI group included 72 patients. According to the Neer classification, there were 46 cases of two-part fracture, 63 cases of three-part fracture and 8 cases of four-part fracture. In MI group, there were 17 males and 28 males with an average age of (62.2±17.1) years, including 18 cases of two-part fracture, 23 cases of three-part fracture and 4 cases of four-part fracture. In non-MI group, there were 27 males and 45 females with an average age of (60.1±17.7) years, including 28 cases of two-part fracture, 40 cases of three-part fracture and 4 cases of four-part fracture. There were no significant differences between the two groups in terms of gender (P=0.975), age (P=0.545) and fracture type (P=0.756). The average hospital-stay in MI group and non-MI group was (2.8±1.1) days and (4.3±1.3) days (P=0.023), the operation time was (67.8±14.9) min and (102.3±34.1) min (P<0.001), the blood loss was (21.3±6.5) mL and (181.5±55.6) mL (P<0.001), the Constant-Murley score was 6.1±0.9 and 6.5±0.8 (P=0.032) one week after surgery, and the Constant-Murley score was 66.1±4.3 and 63.4±4.9 (P=0.006) three months after surgery, MI group had significant advantages in these aspects. In terms of Neer two-part and three-part fracture, the VAS score (5.9±0.8) one week postoperatively and the Constant-Murley score (66.6±3.7) three months postoperatively were significantly superior in MI group (P<0.05). In MI group, delayed fracture healing occurred in 1 case (2.2%) and abduction was restricted in 1 case (2.2%). In non-MI group, delayed fracture healing occurred in 3 cases (4.2%) and abduction was restricted in 2 cases (2.8%). There were no internal fixation complications and humeral head necrosis in both groups.Conclusion: Applying the modified internal fixation in MIPPO to cure proximal humeral fractures is effective clinically with thick callus formation occurring at the fracture site. The fracture can achieve normal healing and the shoulder functions can restore well, indicating the modified surgical method is a good treatment option.