Conjoint fascial sheath (CFS) suspension has been gradually recognized and accepted for the treatment of congenital severe blepharoptosis in recent years. To address the problem of postoperative upper eyelid position regression of only CFS suspension, we designed and implemented a CFS combined Levator muscle (CFS+LM) complex flap. This research aims to analyze the surgical efficacy of CFS+LM and FMF suspension surgery.Patients diagnosed with congenital severe ptosis with levator muscle function ≦4 mm were enrolled. According to the surgical method, the patients were divided into the CFS+LM and FMF groups. To compare and statistically analyze the postoperative effect between CFS+LM and FMF suspension.Data from 182 patients (220 eyes) were collected in this study, including 89 patients (103 eyes) in the CFS+LM group and 93 patients (117 eyes) in the FMF group. The full correction rate, patient satisfaction, postoperative upper eyelid excursion and lagophthalmos in the CFS+LM group were significantly better than those in the FMF group. The eyelid retraction rate was significantly higher in the FMF group than in the CFS+LM group. The complication rate in the CFS+LM group was significantly lower than that in the FMF group.CFS+LM suspension had better outcomes than FMF. Considering that the CFS tissue could be weak in patients under 5 years old and have poor muscle elasticity in patients with levator muscle function ≤1 mm, FMF suspension is firstly recommended. For patients over 5 years old with severe ptosis, CFS+LM suspension is recommended.Copyright © 2023 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Society of Plastic Surgeons. All rights reserved.