Objective: To compare the clinical efficacy of sub-brow incision surgery and double eyelid formation surgery in treating moderate to severe upper eyelid skin laxity. Methods: A total of 88 patients with moderate to severe upper eyelid skin laxity admitted from April 2023 to September 2025 were randomly divided into an observation group (sub-brow incision surgery) and a control group (double eyelid formation surgery), with 44 cases in each group. The postoperative 6-month surgical efficacy rates, upper eyelid skin coverage, bilateral symmetry differences, postoperative 3-month upper visual field average acuity, postoperative 3 and 6-month scar scores (VSS, POSAS), complication rates, and 6-month patient satisfaction (VAS scores) were compared between the two groups. Results: The observation group showed significantly better surgical efficacy rates (95.45% vs 81.82%), postoperative upper eyelid skin coverage (1.12±0.21 mm vs 1.58±0.44 mm), bilateral symmetry differences (0.18±0.05 mm vs 0.34±0.11 mm), postoperative 3-month upper visual field average acuity (27.85±2.31 dB vs 25.63±2.19 dB), and patient satisfaction VAS scores (8.63±0.94 points vs 7.21±1.13 points) compared to the control group (all P<0.05). The observation group also had lower VSS scores (1.93±0.64 points vs 3.15±0.93 points) and POSAS scores (13.47±2.85 points vs 18.92±3.64 points) at 3 and 6 months postoperatively, as well as a lower total complication rate (6.82% vs 25.00%) compared to the control group (all P<0.05). Conclusion: For moderate to severe upper eyelid skin laxity, sub-brow incision surgery demonstrates superior outcomes in correction, visual field improvement, scar concealment, complication reduction, and patient satisfaction compared to traditional double eyelid formation surgery.