Objective: To analyze the prognostic factors affecting the failure of transvaginal repair of vesicovaginal fistula (VVF). Methods: A retrospective nested case-control study was conducted. A total of 15 patients who underwent unsuccessful transvaginal vesicovaginal fistula repair in the Department of Urology, Peking University First Hospital from January 2014 to December 2020 were enrolled as the case group. A total of 60 patients receiving transvaginal vesicovaginal fistula repair by the same surgeon within the same time range, were selected as the control group. The age, body mass index (BMI), etiology of vesicovaginal fistula, associated genitourinary malformation, frequency of repair, characteristics of fistula, surgical procedure, postoperative recovery and other factors were compared between the case group and the control group, and the influencing factors of failure were analyzed. Results: The BMI of the case group was (26.3±3.9) kg/m², the diameter of vaginal fistula was (1.5±0.8) cm, and the operative time of transvaginal repair was (111.8±19.8) min. The proportion of the patients with genitourinary malformations was 4/15, the proportion of the patients with multiple vaginal repairs was 13/15, the proportion of the patients with concurrent ureteral reimplantation was 6/15, and the proportion of the patients with postoperative fever was 5/15. In the control group, the BMI was (23.9±3.0) kg/m², the diameter of vaginal fistula was (0.8±0.5) cm, the operative time of transvaginal repair was (99.9±19.7) min, the rate of associated genitourinary malformation was 2/60, the rate of multiple transvaginal repair was 18/60, the rate of concurrent ureteral reimplantation was 5/60, and no postoperative fever was found. Compared with the control group, the case group had higher BMI (P=0.013), bigger vaginal fistula (P=0.002), longer time of operation (P=0.027), higher proportion of genitourinary malformations (P=0.013), higher proportion of repeated transvaginal repair (P<0.001), higher proportion of ureter reimplantation (P=0.006), and higher proportion of postoperative fever (P<0.001). Multivariate analysis showed that fistula diameter ≥1 cm (OR=10.45, 95%CI=1.90-57.56, P=0.007) and repeated transvaginal repair (OR=16.97, 95%CI=3.17-90.91, P=0.001) were independent prognostic factors for VVF failure in transvaginal repair. Conclusion: Fistula diameter ≥1 cm and repeated transvaginal repair are independent prognostic factors of failure in transvaginal repair.