Abstract: Objective To simulate the biomechanical characteristics of pelvic-ligament-muscle during vaginal delivery and rest, and to explore the injury of levator ani muscle in vaginal delivery, pelvic organ prolapse and stress urinary incontinence. To provide a mechanical basis for clinical treatment of pelvic organ prolapse and stress urinary incontinence. Methods A three-dimensional finite element model of pelvis-ligament-muscle was established to calculate the stress-strain distribution, displacement and injury of levator ani muscle under 7 different working conditions (tension, abdominal pressure, load changes).The stress-strain distribution, displacement and injury of type I stress urinary incontinence, type II stress urinary incontinence, type III stress urinary incontinence and organ prolapse were calculated. Results Vaginal delivery, organ prolapse, type I stress urinary incontinence, type II stress urinary incontinence, type III stress urinary incontinence, the maximum stress position of type III stress urinary incontinence appears in the middle of the puborectal muscle and the junction of the puborectal muscle and the obturator muscle. Conclusion Vaginal delivery, organ prolapse, type I stress urinary incontinence, type II stress urinary incontinence, type III stress urinary incontinence damaged the same parts.Spontaneous delivery can easily lead to organ prolapse, type I stress urinary incontinence, type II stress urinary incontinence, type III stress urinary incontinence, and the vulnerable sites are in the middle of the puborectal muscle and the junction of the puborectal muscle and the obturator muscle.