CIN in medicine stands for precancerous lesions, and the most common one in gynecology is the localized CIN of the cervix, which is divided into 3 levels, CIN1, CIN2 and CIN3. Once CIN is found in the epithelium of the cervix, appropriate treatment should be given. In the case of CIN grade 1, physical therapy of the cervix can be done, mainly to make the local lesion tissue necrotic, shed and grow new tissue to achieve the purpose of treatment. In case of CIN grade 2 or CIN grade 3, which are high grade precancerous lesions, cold knife conization of the cervix is recommended to remove the lesions, which can also achieve the purpose of treatment.