Lateral drainage is an important way for the middle and lower rectum. There are still disputes between Eastern and Western scholars regarding the treatment strategy of lateral lymph node metastasis. It is difficult to diagnose lateral lymph node metastasis by pathologic examination before surgery. MRI is the main method for diagnosis of lateral lymph node metastasis in rectal cancer. The diagnostic criteria for patients before and after neoadjuvant treatment are slightly different. CT， PET/CT and radiomics also have certain advantages in the diagnosis of lateral lymph node metastasis. If necessary， the combination of multiple methods can help in the diagnosis of lateral lymph node metastasis.