Abstract: Middle and low rectal cancer is one of the most common colorectal cancers. The lymph node metastasis, especially primary lymph node metastasis, is an important factor affecting prognosis of middle and low rectal cancer. Inferior mesenteric artery root lymph nodes and lateral lymph nodes are the primary lymph nodes of middle and low rectal cancer in different drainage direction. Based on literatures and clinical experiences, the author discusses the characteristics, main areas, clinical significance of metastasis, range of dissection and operation methods of the above two lymphatic drainage way, to find out the focus of controversy. The author advocates to focus on the clinical and basic researches of related problems and make more appropriate clinical decisions to improve the curative effect of middle and low rectal cancer.