Reasonable nutrition therapy is closely related to the treatment and prognosis of tumor patients which is not only helpful to improve the quality of life of tumor patients and reduce the complications but also can reduce the treatment cost. The survey results of the Professional Committee of Tumor Nutrition Therapy of China Anti-Cancer Association show that the overall malnutrition incidence rate of inpatient tumor patients in tertiary hospitals in China is 80. 4% while the nutrition treatment rate of malnourished patients is only 33. 7%. The current lack of attention to nutrition diagnosis and treatment of tumor patients and the lack of high-level clinical evidence-based evidence seriously restrict the standardized diagnosis and treatment of tumor patients and the improvement of the overall diagnosis and treatment of tumor. 2021 based on the continuous efforts of scholars at home and abroad the epidemiology of nutritional status of malignant tumor patients the improvement of malnutrition assessment and diagnosis the recommendation of dietary structure tumor nutrition treatment and predictive index and the special population These researches have provided high - level and precise evidence-based medical evidence for the clinical problems that exist and need to be solved and have made the development direction of the field of oncology nutrition clearer.