Rectal mucinous adenocarcinoma is not the most serious type of rectal cancer. Rectal cancer is classified into adenocarcinoma, adenosquamous carcinoma and undifferentiated carcinoma according to its histologic classification. Rectal mucinous adenocarcinoma is a kind of adenocarcinoma, and the pathologic manifestation is that the cancer cells secrete a large amount of mucus. Among these three types of rectal cancer, adenocarcinoma is the more common type with a relatively low degree of malignancy, while undifferentiated carcinoma has the highest degree of malignancy and the worst prognosis. Both rectal mucinous adenocarcinoma and undifferentiated carcinoma will show symptoms of blood in the stool, change in stool character and habit, anal pain and intestinal stenosis, and the difference lies in the type of pathology. Once diagnosed, linear mucinous carcinoma is usually treated by surgery, supplemented by radiotherapy, chemotherapy and targeted therapy. Firstly, the rectum is selectively resected according to the invasion range of cancer cells, and radiotherapy, chemotherapy and targeted therapy are used to kill tumor cells and inhibit the growth and reproduction of tumor cells. During the treatment period, patients with rectal mucinous carcinoma should pay attention to light diet, regulate their emotion, keep their mood relaxed, and avoid eating barbecue and high-fat food, which is conducive to controlling the development of the disease.