CIN is a medical term for cervical intraepithelial neoplasia, which is a continuous process of cervical epithelial atypical hyperplasia to carcinoma in situ, associated with high-risk human papillomavirus infection, and is a precancerous lesion. According to the degree of atypical hyperplasia, CIN is divided into three levels, the first level is mild typical hyperplasia with heterogeneous cells confined to the lower 1/3 of the epithelial layer, the second level is moderate atypical hyperplasia with heterogeneous cells occupying 1/2-2/3 of the epithelial layer, and the third level is severe atypical hyperplasia and carcinoma in situ with increased nuclear division phase. Cervical intraepithelial neoplasia is associated with human papillomavirus infection, smoking and immunodeficiency diseases. It is recommended to actively prevent and treat high-risk HPV positivity, and actively exercise to enhance physical fitness.