ObjectiveFurther understand the mechanisms of malnutrition in patients with gastric cancer (GC) and which affecting on therapy outcomes, and explore effective nutritional intervention strategies so as to improve general therapy outcomes for patients with GC. MethodThe literature on studies relevant malnutrition in the patients with GC both domestically and internationally was reviewed and analyzed. ResultsThe mechanisms of malnutrition in the patients with GC are complex and diverse, including abnormal tumor metabolism, side effects of treatment, psychological and economic factors, etc. The malnutrition made the mortality and recurrence rates increase, hospital stay prolong, and medical costs elevate, meanwhile led to the multiple complications. The use of various screening tools could effectively assess the malnutrition status at the different therapy stages, then the individualized nutritional therapy plans could be developed based on the assessment results. These plans included oral nutrition, enteral nutrition, parenteral nutrition, and immunonutrition. ConclusionsMalnutrition severely affects the treatment outcomes and quality of life of patients with GC, necessitating timely screening and assessment. The reasonable nutritional support plan should be chosen based on the patient’s individualized situation. Future research should further explore the long-term efficacy and safety of nutritional support, optimize the application of immunonutrition and parenteral nutrition, and enhance the general treatment outcomes for patients with GC.