Rectal cancer liver metastasis belongs to stage IV, and the survival rate of stage IV rectal cancer is around 10%-30% within five years after regular standard treatment. One to three years after surgery is the high incidence period of recurrent metastasis for rectal cancer patients, 80% of recurrent metastasis occurs within three years after surgery, 95% of recurrent metastasis occurs within five years after surgery, if rectal cancer liver metastasis lives for forty years that is a cure. Tumor T, N, M staging method consists of three basic analysis elements, T staging refers to the situation of tumor primary foci, with the increase of tumor volume, the depth of infiltration and the scope of involvement of neighboring tissues, in order to use T1 to T4, N staging refers to the situation of regional lymph node involvement, with the lymph nodes uninvolved by N0, with the increase of lymph node involvement and degree, in order to use N1-N2, M staging refers to distant metastasis, without the involvement of lymph nodes, with the increase of lymph nodes, with N1-N2, M Stage refers to distant metastasis, without distant metastasis, it is indicated by M0, and with distant metastasis, it is indicated by M1. For stage IV patients, the tumor has distant metastasis, but if this metastasis is single or limited, it is possible to remove all the tumor by surgery, and then give the patient comprehensive treatment after surgery, including chemotherapy, targeted therapy, immunotherapy and other supportive treatments, and this kind of patients still have the possibility of cure.