To explore the detection rate, clinical characteristics of vulvar squamous intraepithelial lesion (SIL). Women diagnosed with vulvar high-grade squamous intraepithelial lesions (HSIL) through colposcopy-guided biopsy from January 1, 2018 to August 31, 2022 in Obstetrics and Gynecology Hospital of Fudan University were included in a 1∶1 ratio with patients diagnosed with vulvar low-grade squamous intraepithelial lesions (LSIL) during the same period. Clinical characteristics including human papillomavirus (HPV) infection rate, genotype, cytology result, colposcopy impression, and lesion location were retrospectively analyzed. (1) The proportion of vulvar SIL detected by colposcopy-guided biopsy increased annually from 2018 to 2022, with rates of 1.64% (740/45 057), 2.34% (1 110/47 402), 2.68% (1 108/41 335), 3.26% (1 536/47 078), 3.31% (667/20 155), with an average rate of 2.57% (5 161/201 027). (2) A total of 1 096 cases of vulvar HSIL and 1 096 cases of vulvar LSIL were included. The overall infection rate of HPV was 92.7% (1 993/2 150), with higher infection rate in vulvar HSIL patients than that in vulvar LSIL patients [96.0% (1 012/1 054) vs 89.5% (981/1 096); =33.62, <0.001]. Among vulvar HSIL patients, the common HPV genotype from high to low were HPV 16 (66.7%), HPV 52 (14.3%), and HPV 58 (10.0%). For vulvar LSIL patients, the most common HPV genotype were respectively HPV 16 (24.9%), HPV 6 (20.1%) and HPV 52 (17.1%). The overall sensitivity rate of cytology was 53.6%, with no significance difference between vulvar LSIL and HSIL groups (54.3% vs 52.9%; =0.40, =0.526). The accuracy of colposcopy impression for vulvar HSIL was lower than that for vulvar LSIL [40.2% (163/405) vs 81.7% (380/465); =158.72, <0.001]. About 57.3% (1 257/2 192) of the patients had concomitant cervical and vaginal lesions, with a higher rate in vulvar HSIL group than that in vulvar LSIL group [62.6% (686/1 096) vs 52.1% (571/1 096); =24.67, <0.001]. Unifocal lesion was the main type, with no significance difference between vulvar LSIL and HSIL groups [81.4% (381/468) vs 82.5% (386/468); =0.18, =0.671]. The most common lesion locations were the posterior commissure, followed by labia minora, vaginal vestibule, labia majora, perianal and clitoris. The detection rate of vulvar SIL under colposcopy is about 3%, and the infection rate of HPV is 92.7%. Vulvar SIL, especially vulvar HSIL, is likely to cause concomitant cervical and vaginal lesions. The accuracy of colposcopy in diagnosing vulvar HSIL is low. Therefore a comprehensive and careful examination of the vulva is necessary and suspicious vulvar lesions should be undergone colposcopy-guided biopsy for diagnosis.