To investigate the therapeutic effect of open reduction and internal fixation (ORIF) on supination external rotation (SER) ankle fractures (AF) and its impact on ankle joint function and range of motion in patients.Methods:The observation group patients were treated with ORIF, while the control group patients were treated with manual reduction combined with plaster external fixation. Both groups of patients were followed up after 3 and 6 months of treatment. Compare the ankle joint function levels of two groups of patients before treatment and after 3 and 6 months of treatment (Kofood score, AOFAS score, Olerud Molander subjective ankle score (OMAS)). Compare the joint range of motion (relative peak force, torque acceleration energy, endurance) between two groups of patients after 3 and 6 months of treatment. Compare the clinical indicators and incidence of adverse events between two groups of patients after 6 months of treatment. T-test was used for comparison between two groups. Multiple group comparisons were conducted using analysis of variance, while pairwise comparisons were conducted using Dunnett-t test. Comparison of count data between groups using χ2 inspections or Fisher exact test. Results:Before treatment, there was no statistically significant difference in the Kofoed score, AOFAS score, and OMAS score between the two groups of patients (all P>0.05). The Kofoed scores of patients in the observation group before treatment and at 3 and 6 months of treatment were (53.78±6.40), (76.73±4.12), and (89.07±5.78) points, respectively. The control group was (52.22±7.08), (71.68±4.82), and (84.05±5.45) points, respectively. The Kofoed scores of patients in both groups were higher than before treatment at 3 and 6 months of treatment (all P<0.05), and the observation group was higher than the control group (all P<0.01).The AOFAS scores of patients in the observation group before treatment and at 3 and 6 months of treatment were (70.13±5.39), (81.62±4.25), and (92.05±4.15) points, respectively. The control group was (69.85±5.41), (79.08±4.60), and (88.92±4.43) points, respectively. The AOFAS scores of patients in both groups were higher than before treatment at 3 and 6 months of treatment (all P<0.05), and the observation group was significantly higher than the control group (all P<0.01).The OMAS scores of the observation group patients before treatment and at 3 and 6 months of treatment were (53.43±5.07), (76.14±4.52), and (85.68±4.14) points, respectively. The control group was (54.42±4.86), (71.39±3.94), and (81.78±4.15) points, respectively. The OMAS scores of the two groups of patients at 3 and 6 months of treatment were higher than before treatment (all P<0.05), and the observation group was higher than the control group (all P<0.01). The fracture healing time (38.85±4.50) days and complete weight-bearing time (66.62±7.14) days of the observation group patients were shorter than those of the control group patients (49.42±5.43) days and (74.39±6.75) days, and the differences between the two groups were statistically significant (t-values were 12.89 and 6.80, respectively, all P<0.01); There was no statistically significant difference in the incidence of adverse events between the two groups of patients (5.41% (4/74) and 9.46% (7/74)), χ2=0.88, P=0.347). Conclusion:ORIF has a good therapeutic effect on SER-AF patients, promotes ankle joint function recovery, and has a low incidence of adverse events, indicating good safety.