Rectal cancer is one of the most common malignant tumors of digestive system. Accurate preoperative diagnosis plays an important role in surgeons′ decision on treatment plan. Extramural venous invasion (EMVI), as an important prognostic factor for predicting lymph node metastasis, distant metastasis and overall survival time of rectal cancer, has been paid more attention in recent years. It may even be used as a new staging system for guiding clinical treatment and formulate accurate preoperative staging. Preoperative MRI(mrEMVI) and postoperative pathology (pEMVI) is equal in the accuracy of assessment of EMVI. mrEMVI can be used as an important item for preoperative multi disciplinary team or clinicians to evaluate the patient stage and formulate individual treatment plan, and can also be used as an important evaluation for whether to perform surgery after preoperative chemoradiotherapy (CRT) and whether to prolong postoperative chemoradiotherapy time. EMVI should be taken as one of the necessary preoperative examinations for all the rectal cancer patients.