1）Improve each examination 1）Three major routine: blood routine, urine routine, fecal routine. (2) Blood tests: ① blood type, ② coagulation function, ③ eight items before transfusion, ④ blood biochemical tests (including liver and kidney function). (3) Routine electrocardiogram examination. 4）Frontal and lateral X-ray of the chest. 5）Electronic colonoscopy and pathology examination. 6）Whole abdominal multi-row CT enhancement. Selective dynamic ECG, cardiac ultrasound, cardiac dual-source CT, pulmonary function, pelvic MRI, enterography, and other examinations are done as needed. (1) Colorectal cancer patients with anemia are common: appropriate amount of blood transfusion should be given to correct the anemia. (2) Hypertension: take oral hypotensive drugs such as Lowe’s and Captopril. (3) Diabetes mellitus: stop oral hypoglycemic drugs and change to insulin injection. (3) To reduce intraoperative contamination and facilitate postoperative recovery, intestinal preparation should be done. (1) Generally, fasting starts in the afternoon 1 day before surgery, and bowel cleansing starts at 16:00 to 17:00 pm (after drinking 1000 to 2000 ml of bowel cleansing liquid within 1 to 2 hours, bowel movement starts) (2) Patients with incomplete obstruction (colonoscopy cannot pass through the tumor site, or no bowel movement but there is exhaustion) should have intestinal slag-free nutrition or adopt fasting for the sake of safety, and prohibit eating fierce laxatives to prevent acute bowel obstruction or fecal perforation! You can take 30ml of paraffin oil orally 3 times/day for 3 to 5 days each time, and rehydrate for nutritional support. (3) Complete obstruction (no defecation and no exhaustion) requires emergency surgery, no intestinal preparation. IV. Skin preparation. (1) All hair in the surgical area such as abdomen and perineum should be shaved. (2) In order to show a good image after surgery, it is better to cut hair and shave.