To evaluate and validate the safety and efficacy of modified laparoscopic sacrocolpopexy for advanced posterior vaginal wall prolapse at up to 3 years of follow-up. As a prospective observational study, we collected 56 cases with advanced posterior vaginal wall prolapse and performed modified laparoscopic sacrocolpopexy (MLSC) with self-cut mesh. The main improvement is the cutting and fixing of the mesh. Patients were followed up at 6, 12, 24 and 36 months. The main indicators of follow-up were postoperative anatomic success rate and Pelvic organ prolapse quantitation (POP-Q) score, and secondary indicators were related to quality-of-life scales and postoperative complication rates. All patients completed the operation through minimally invasive surgery, and there were no vital organs and blood vessel damage during the operation. The mean age was (58.32 ± 7.63) years. There was no recurrence of stage I or lower during the follow-up maximum of 36 months (median 24 months), and the anatomic success rate was 100%. The quality-of-life scores improved significantly (p < 0.001) and the quality of sexual life was not affected (p = 0.5). There was 1 case of continuous vaginal mesh exposure at 12 months (2.86%) and 1 case of severe infection with poor healing of vaginal stump within 6 months (1.79%). No one had urinary incontinence (UI) requiring reoperation. In patients with advanced posterior vaginal wall prolapse, MLSC can provide good and durable pelvic floor anatomical recovery and functional outcomes with no specific complications.