The first and most common site of rectal cancer bloodstream metastasis is liver, followed by lung, bone and brain, etc. Generally, rectal cancer rarely metastasizes to adrenal gland and kidney. There are four main diffusion and metastasis pathways of rectal cancer, which are analyzed as follows: First, local diffusion: firstly, it spreads in the intestinal wall, and the intestinal tumor has to surround the intestinal wall for a week, which takes about two years to grow. Second, lymphatic tract metastasis: the metastatic pathway is lymphatic tract metastasis, which accounts for about 60%. Third, hematogenous metastasis: the most common metastasis is to liver, lung and so on. Fourth, implantation metastasis: cancer cells of intestinal cancer will be shed and planted in the abdominal cavity or pelvic cavity to form nodes, which is also a way of rectal cancer metastasis.