Objective: To assess the efficacy of open reduction internal fixation (ORIF) combined with fixed-time and fixedangle external fixation (FTFAEF) in the treatment of Gartland type III supracondylar humerous fracture (SHF) in children. Methods: Clinical data of 172 children with Gartland type III SHF from March 2012 to December 2017 were prospectively analyzed. All 172 patients were initially treated with ORIF, then 86 underwent FTFAEF for 3 weeks post-surgery (intervention group) while the remaining 86 received conventional plaster external fixation (70°-90°) for 3 weeks post-surgery (control group). The plaster casts were removed from both groups after the 3-week fixation period and functional exercise was initiated. Regular clinical and radiologic follow-ups were conducted on all patients. Range of motion (ROM) measurements and modified Hospital for Special Surgery (HSS) elbow function assessments were performed at 1 and 3 months post-surgery. Results: At 1 month post-surgery, both ROM and modified HSS scores were significantly higher in the intervention group (85.8±6.1° and 65.2±3.6°, respectively) than in the control group (62.3±5.2° and 56.6±2.1°, respectively)(both P<0.05). After 3 months, both ROM and modified HSS scores were still significantly higher in the intervention group (132.0±4.7° and 98.5±1.3°, respectively) than in the control group (107.5±24.4° and 85.0±10.3°, respectively) (both P<0.05). Furthermore, the percentage of patients scoring excellent on the HSS scale was significantly higher in the intervention group (100%) than in the control group (74.42%) (P<0.05). Conclusions: ORIF combined with FTFAEF is an efficacious approach that should be widely promoted for the treatment of Gartland type III SHF in children.