Malignancy has become the focus of studies around the world. Patients with cancer are prone to be malnourished and cancer-related malnutrition results from multiple factors. In addition to the malignancies itself the direct cause of death in 20% of cancer patients is nutritional deficiency and progressive cachexia. Malnutrition reduces the immunity and anti-infection ability of the body leads to the decrease of tolerance and sensitivity during chemotherapy and seriously affects the quality of life and prognosis. The incidence of nutritional risk in cancer patients is 40% - 70% . Early screening of nutritional risks in patients with cancer during chemotherapy and giving adequate and reasonable nutritional support to change their malnutrition is a major problem to be solved at present. Numbers of studies have shown that nutritional therapy during chemotherapy can significantly improve the malnutrition status of patients and have a positive impact on the prognosis. A comprehensive treatment mode based on five-step nutrition therapy has been gradually developed. Some new supplements and drugs for improving nutritional status have shown unique efficacy in clinical studies and animal trials. Large - scale prospective clinical trials are aimed at exploring effective means to improve nutritional status and prognosis. Nutritional therapy runs through antitumor therapy We discussed the nutritional status of cancer patients as well as the causes during chemotherapy and nutritional support therapy in perichemotherapy was reviewed.