Cervical neoplasia, medically known as cervical intraepithelial neoplasia, or CIN for short, is a group of cervical lesions closely related to cervical invasive carcinoma, which often occurs in women aged 25-35 years. The onset is mainly related to human papillomavirus (HPV) infection, especially the high-risk HPV 16 and 18 infection. CIN is classified into 3 grades, most of the low grade lesions (CINI grade) can regress spontaneously, while high grade lesions (CIN grade II and III) have cancer potential and are considered as cervical precancerous lesions. CIN is divided into three types, which are CINI grade when the lesion cells are confined to the lower 1/3 layer of squamous cells in the cervical complex, CIN grade II if more than 1/3 but confined to 2/3 layer, CIN grade III if more than 2/3, and called cervical carcinoma in situ when the whole layer is reached. CIN grade I: mild heterogeneity, about 60% will regress spontaneously. If the cytology is LSIL or below, it can be observed and followed up only, and if the lesion develops or persists for 2 years in the process, treatment is appropriate. If the cytology is HSIL (high degree of squamous intraepithelial lesions) treatment should be given, with cryotherapy and laser treatment for satisfactory colposcopy, and cervical conization recommended for those who are not satisfied or have a positive cervical canal scraping. CIN grade II and CIN grade III: About 20% of grade II will develop into grade III and 5% into invasive carcinoma, so both grade II and III lesions need treatment. Colposcopic satisfactory grade II can be treated with physical therapy or cervical conization. Unsatisfactory grade II and all grade III should be treated with cervical conization, such as cervical loop electrosurgery (LEEP) or cold knife conization. Cervical intraepithelial neoplasia (CIN) reflects the continuous process in the development of cervical cancer. Screening to detect CIN and timely treatment of high-grade lesions is a proven measure to prevent cervical cancer.