The diagnosis of neuroendocrine tumors should be classified based on the degree of differentiation and grading of the tumor, in addition to identifying the site of tumor occurrence. The histological classification of neuroendocrine tumors is very important for treatment decisions as well as prognosis determination. According to the 2010 WHO classification, gastroenteropancreatic neuroendocrine tumors are classified as: neuroendocrine tumors, grade 1 (carcinoid tumor); neuroendocrine tumors, grade 2; neuroendocrine carcinomas, grade 3, including large cell neuroendocrine carcinoma, small cell neuroendocrine carcinoma; and mixed glandular neuroendocrine carcinoma. Even for neuroendocrine tumors in the same site, if the tumors are of different grades, they are not equally sensitive to various therapies. Lowly differentiated neuroendocrine carcinoma has rapid tumor development and poor prognosis, but these tumors are more sensitive to chemotherapy. Highly differentiated neuroendocrine tumors often do not need chemotherapy after surgery, and chemotherapy is not advocated for patients with advanced stage (chemotherapy is not sensitive), and other western and Chinese medications can be adopted. Doctors must choose the appropriate treatment according to the different conditions of patients. Therefore, clinicians attach great importance to the accuracy and authority of each patient’s pathology report.