Objective To study the effects of modified pelvic floor reconstruction on systemic stress, pelvic floor muscle strength, and surgical outcomes in elderly patients with severe pelvic organ prolapse (POP). Methods A total of 146 elderly patients with predominant anterior vaginal wall prolapse accompanied by varying degrees of uterine prolapse and posterior vaginal wall prolapse admitted to Shanghai First Maternity and Infant Hospital from June 2021 to June 2024 were selected as study subjects. According to the surgical procedure, they were divided into a modified reconstruction group (modified pelvic floor reconstruction with transvaginal implantation of TiLOOP mesh, n=80) and a control group (vaginal hysterectomy combined with vaginal wall repair, n=66). Perioperative indicators were collected in both groups. Systemic stress response in the two groups was evaluated at 1 day after surgery, pelvic floor muscle strength at 3 months after surgery, and anatomical recovery conditions of pelvic organ prolapse quantitation (POP-Q) sites at 1 year after surgery. Cure rates at 3 months, 6 months, and 1 year after surgery and postoperative complications were statistically analyzed. Data analysis was performed by using SPSS 27.0. Depending on the data type, between-group comparisons were conducted using the independent samples t-test, paired samples t-test, Chi-square test, or Fisher′s exact test. Results The modified reconstruction group had significantly shorter surgical time, postoperative anal exhaust time, and postoperative hospital stay, less intraoperative blood loss, and lower numeric rating scale (NRS) scores at 48 h after surgery than the control group (all P<0.05). At 1 day after surgery, the levels of peripheral blood corticosteroids (Cs) and adrenocorticotropic hormone (ACTH) in the two groups increased compared with those in the same group before treatment, and the levels of peripheral blood Cs and ACTH in the modified reconstruction group were lower than those in the control group (both P<0.05). At 3 months after surgery, resting tension, dynamic tension, contractility and electromyographic potential of pelvic floor muscles increased in the two groups compared with values before surgery, and the indicators in the modified reconstruction group were higher than those in the control group (all P<0.05). At 1 year after surgery, the anatomical positions of POP-Q pelvic sites were significantly improved in the two groups compared with those before surgery, and the anatomical positions of POP-Q pelvic sites were better in the modified reconstruction group than those in the control group (all P<0.05). There was no statistical significance in the cure rate between the two groups at 3 months after surgery (P=0.845). The cure rates in the modified reconstruction group at 6 months and 1 year after surgery were higher than those in the control group (both P<0.05). No pelvic organ injury occurred in either group during surgery, and there were no statistical differences in the incidence of postoperative complications (all P>0.05). Conclusion Modified pelvic floor reconstruction has less surgical trauma and lower systemic stress response, and can effectively enhance the pelvic muscle strength in elderly patients with severe POP, restore the anatomical positions of POP-Q pelvic sites, and provide stable efficacy at 1 year after surgery.