The main treatments for rectal cancer include surgery, radiotherapy and chemotherapy. For the treatment of high-grade rectal cancer, performing surgery is the main cure method for rectal cancer, and preoperative neoadjuvant and postoperative adjuvant radiotherapy can improve the cure rate to some extent. Specific methods are as follows: 1. Surgery: sharp removal of tumor through fine surgery is one of the best treatment methods. The surgical method can be selected according to comprehensive factors such as tumor location, stage, cell grading, body type and stool control ability. Clinical research suggests that the infiltration of rectal cancer into the distal intestinal wall is smaller than that of colon cancer, and only 2% of rectal cancer infiltrates more than 2cm into the distal end, which is one of the important bases for choosing surgery; 2. radiotherapy: radiotherapy in the perioperative period can improve the chance of cure, and palliative radiotherapy can relieve symptoms; 3. chemotherapy: the routes of administration include systemic intravenous administration, postoperative intraperitoneal heat infusion chemotherapy, etc. Chemotherapy for colorectal cancer is based on fluorouracil, and systemic intravenous chemotherapy is the main treatment; 4.Other treatment: if rectal cancer forms obstruction and cannot be operated, local treatment by cauterization, laser or freezing can be used, or metal stent can be placed to release intestinal obstruction and reduce the symptoms of intestinal obstruction. For multiple liver metastases that cannot be removed by surgery, interventional ablation therapy or embolization therapy under the guidance of ultrasound or CT can be used to improve the quality of life of patients as the main goal.