I. Clear diagnosis. Pathological diagnosis is the gold standard for the diagnosis of malignant tumor, therefore, patients suspected of colorectal cancer should obtain tumor tissues for pathological examination through colonoscopy or puncture of metastases to make a clear diagnosis. Second, comprehensive assessment. Through imaging, laboratory tests, cardiopulmonary function and other examinations, we should understand whether the physical condition can withstand surgery, whether the disease stage is suitable for surgery, and whether tumor markers such as CEA are increased (which is crucial to the evaluation of patient’s treatment effect). Third, determine the postoperative pathological stage. According to the postoperative pathological stage of operable patients, further treatment plan should be formulated; T3N0M0, especially colon cancer with high-risk factors (tumor hypofractionation, lymphatic/vascular infiltration, intestinal obstruction, less than 12 resected lymph nodes), T4N0M0 and cases with lymph node metastasis or distant metastasis should undergo postoperative adjuvant chemotherapy. Fourth, patients who cannot be treated surgically should receive chemotherapy directly.