Adenocarcinoma in situ of the uterine cervix is a cancer of the cervical epithelium that has not broken through the basement membrane without infiltration. Adenocarcinoma in situ of the cervix starts from the transformation zone and can involve both the surface glandular epithelium and the deeper glands of the endocervical canal in a multifocal manner. The main pathological features are increased atypia, increased nucleoplasmic ratio, nuclear anisotropy, nuclear heterogeneity, and disorganized polarity, but with an intact basement membrane. The outline of the gland is normal or abnormal, such as inflexion, convexity and angularity, or papillary protrusion into the lumen. The depth of the cancerous gland does not exceed the depth of the surrounding normal glands, and there is no infiltration or necrosis in the interstitium. As long as the cancer is detected early and surgical excision is performed, the result is still very good and the prognosis is relatively good. Whether it is adenocarcinoma in situ or squamous carcinoma in situ, it has a lot to do with viral infection, premature sexual intercourse, and non-sexual intercourse. Therefore, women should be clean and have good habits in daily life, and they should be screened for cervical cancer once a year to achieve early detection and treatment.