Rectal cancer and colon cancer are collectively known as colorectal cancer, which is one of the most common malignant tumors. According to relevant information, the incidence of colorectal cancer occupies the 4th place among all malignant tumors, and there is a trend of gradual increase. The age of onset is mostly above 40 years old, and there are more men than women. The occurrence of colorectal cancer is related to chronic inflammation, colorectal polyps, adenoma and certain genetic factors. In addition, the increase of unsaturated polycyclic hydrocarbons caused by high-protein and high-fat diet increases the risk of carcinogenesis, coupled with the decrease of fiber food intake, excessive fecal storage and the accumulation of carcinogenic substances, which easily leads to colorectal cancer. Abdominal obesity and constipation are also high-risk factors of colorectal cancer. Bloody stool or mucopurulent stool, change of stool shape or habit, abdominal pain, abdominal mass, etc. are common in clinical practice. Depending on the site of occurrence, the clinical manifestations are often specific to each stage.