Objective To investigate the application effect of poly-L-lactic acid (PLLA) in patients with senile vaginitis. Methods A total of 50 patients with senile vaginitis admitted to Nanchang Tianrun Cosmetic Medical Clinic from April 2021 to March 2022 were selected as the research objects. PLLA was selected as the intervention factor and vaginal submucosal multipoint injection was used. The vaginal health index, vaginal symptom index and vaginal pH were observed 3 months after operation. Results The vaginal health score after treatment was (9.84±1.69) scores, which was higher than (6.06±2.14) scores before treatment, and the difference was statistically significant (P0.05).Conclusion PLLA can improve the aging symptoms of vaginal mucosa in senile vaginitis, improve the health status of vagina, improve the internal environment of vagina, and has high clinical application value in vaginal rejuvenation.