The colonic plasma membrane is the outermost mesothelial covering of the colon, and the subplasma layer is the structure between the plasma membrane and the extracolonic visceral organ tissues. The colonic intestinal wall is histologically divided from inside to outside into mucosa, submucosa, muscularis propria, and tunica. The colon consists of four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon, of which the outer membrane of the transverse colon and the sigmoid colon, as well as the anterior walls of the ascending and descending colon, are plasma membranes, and the structures between them and the tissues of the extracolonic visceral organs are the submucosal layer. Colonic tissue stratification has important significance for the staging of malignant tumors, and currently the most widely used clinical staging is TNM staging, and if the tumor penetrates the colonic subplasma membrane layer as T4, it belongs to the case that the scope of the lesion is relatively large. It can be simply understood that the larger the tumor volume, the more extensive the growth and dissemination, the worse the patient’s prognosis. Comprehensive analysis with the patient’s individual situation, lymph node metastasis, distant metastasis, etc. is beneficial for doctors to judge the patient’s treatment plan and prognosis.