Genetic testing should be considered after surgery for rectal cancer, which can assess whether the patient is sensitive to chemotherapy, and for advanced patients, it can also guide the need for adjuvant targeted therapy. Rectal cancer is a relatively common malignant tumor of the digestive system in clinic. After surgery, genetic testing can assess the information related to the patient’s pathogenic genes, whether there are corresponding gene mutations, so as to speculate whether there are other malignant tumor risk factors. It can also help to determine whether there is a site of action for targeted drugs and clarify the choice of targeted drugs. It can also assess whether it is sensitive to the corresponding chemotherapeutic drugs and guide the patients’ postoperative chemotherapy program. Therefore, postoperative genetic testing for rectal cancer can help to evaluate the prognosis of patients and guide the choice of treatment plan.