Abstract: Objective To study the efficiency and safety of unilateral sacrospinous ligament fixation（SSLF） in treatment of pelvic organ prolapse（POP）. Methods Clinical data about 80 patients with severe POP who underwent unilateral SSLF in our department from December 2005 to December 2012 were retrospectively analyzed.The patients were followed up from 6th week and 6th month after operation and their POP-Q was scored according to the standard questionnaire investigation and site-specific vaginal examination. Results Seventy（87.5%） out of the 80 patients were followed up with a mean follow-up time of 26.1 months.The average operation time was 52 min,the average blood loss was 83 ml,the average hospital stay time was 6.2 days,the urinary catheter indwelling time was 2.5 days,and the postoperative morbidity was 17.5%.Hematoma was found in the right pelvic of 11 patients（15.7%）,vaginal vault prolapse in 2 patients（2.8%）,stress incontinence in 6 patients（8.6%）,urgent incontinence in 2 patients（2.8%）,and vaginal suture exposure in 5 patients（7.1%）.The Aa,Ba,Ap,Bp and D of POP-Q were significantly different before and after operation（P＜0.01）. Conclusion Unilateral SSLF is a safe and effective procedure for POP,especially for stages 1-3 POP.Its main complications are lumbosacral,buttock and inguinal pain and stress incontinence.