Due to the special metabolic characteristics and the adverse reactions associated with the anti-cancer treatment, the decrease of diet in cancer patients often leads to an increase in the incidence of malnutrition, which is associated with poor clinical outcomes. Previous studies have found that the decrease of some patients’ diet easily ignored by the patients themselves and their clinical medical staffs. Dietary survey is a professional technique to demonstrate the quantity and uality patients eat. However, dietary survey needs professional dietitian to complete, which affects the clinical application. In the earlier studies, the author found that dietary patterns of cancer patients have rules to follow, in accordance with the rules, the diet of patients can be scored. Quantitative for nutrition therapy should be based on the investigation about patients’ intake.