High-grade adeno-epithelial neoplasia and localized carcinoma in the sigmoid colon is the manifestation of malignant transformation of atypical lesions, which belongs to the earliest stage of tumors. After resection of the sigmoid colon lesion, the final pathological result shows that most of the lesions are atypical hyperplastic lesions, with obvious cellular heterogeneity, and it is found that the local cells have been abnormally differentiated, which manifests as malignant cells, and then it is diagnosed as high-grade adeno-endoepithelial neoplasia and localized carcinoma by the final pathological result. It is necessary to make judgment on further treatment of the lesion in combination with the status of the margins. Those with high-grade adeno-epithelial neoplasia of sigmoid colon cancer and localized carcinoma should actively undergo laparoscopic radical surgery for sigmoid colon cancer, and lymph nodes need to be cleared after surgery to avoid tumor recurrence. If bleeding and local pain and discomfort occur after surgery, patients should consult doctor for observation, standardize the treatment under the guidance of clinician, and follow the doctor’s instruction for regular follow-up.