Purpose: To describe our experience with a modified frontal muscle advancement flap to treat patients with severe congenital ptosis. Methods: Analysis of the clinical charts of 154 patients who underwent a modified frontal muscle advancement flap. The FM was exposed by a crease incision. The FM flap was created by deep dissection between the orbicularis muscle and orbital septum from the skin crease incision to the supraorbital margin and subcutaneous dissection from the inferior margin of the eyebrow to 0.5 cm above the eyebrow. No vertical incision was made on the FM flap to ensure an intact flap wide enough to cover the entire upper tarsal plate. Contour, symmetry of height, marginal reflex distance (MRD1), and complications were assessed. Mean follow-up was 10 months. Results: The mean patient age was 7.6 ± 5.6 (range, 2–18) years. The mean MRD1 was 3.2 ± 1.3 mm after the operation. All bilateral cases achieved symmetry and optimal lid contour; 17 unilateral cases were under corrected, with a success rate of 89.0%. Complications such as entropion, exposure keratitis, FM paralysis, frontal hypoesthesia, severe haematoma, and entropion were not observed in our series. Conclusion: A modified frontal muscle advancement flap produced a high success rate with a clear field of vision, mild trauma, and few complications. This technique is relatively simple and should be considered for correcting severe congenital ptosis. Date of registration: 29-03-2020 Trial registration number: ChiCTR2000031364 Registration site: http://www.chictr.org/