Cervical squamous epithelial antigen is a glycoantigen from squamous carcinoma of the uterine cervix, which can appear elevated among various squamous carcinomas in the body. Screening and diagnosis of cervical cancer can be performed by laboratory examination of the squamous epithelium of the uterine cervix. Under normal circumstances, the surface of the cervix is squamous epithelium and is smooth. In case of cervical erosion, that is, when the cervical columnar epithelium is displaced, if there is no leukorrhea abnormality, this is mostly the result of estrogen action and is a normal phenomenon. When the vaginal acidic environment or pathogens act, the out-migrated columnar epithelium is replaced by squamous epithelium, which is called cervical squamous epithelial metaplasia. Cervical squamous intraepithelial lesions, on the other hand, refer to a group of precancerous lesions of the cervix that reflect the process of cervical cancer development and progression. If the degree of lesions is high, it proves that cancer is more likely. In this case, a cervical conization procedure is needed to confirm the nature of the disease. In conclusion, squamous epithelium is present on the surface of the cervix, but under normal circumstances, there is no lesion. If there is metaplasia or lesions, then the surface has cervical disease.