Abstract: A large amount of evidence suggest that vegetarian dietary pattern can significantly reduce the incidence of various malignancies, especially colorectal cancer; while high fat diet and meat are the risk factors for cancer. Different dietary structures directly affect the gut microbiota and their metabolites, thus inducing a tumor prone or tumor suppressive effect. In this article, we reviewed the influence of dietary factors on tumor occurrence, development, and therapeutic effect through regulating the gut microbiota and their metabolic products, in order to provide ideas for the prevention and treatment of malignant tumor.