Dietary components are important for maintaining health and preventing disease. The three major macronutrients including carbohydrates, protein and fat not only supply energy to the body, but also play an important role in tumor nutrition metabolism.Proper amount and high quality carbohydrates can reduce the risk of cancer, and improve the diet with high quality protein supply, high dietary fiber and high ω⁃3 polyunsaturated fatty acids, which has significant benefits to improve the nutritional status and prognosis of cancer patients. Unhealthy diet and other factors can cause intestinal flora imbalance in the body, produce toxic metabolites, induce inflammation and immune imbalance, and promote the occurrence of tumors.A typical Western diet high in saturated fatty acids and refined carbohydrates can disrupt the intestinal barrier,metabolism and nutrition of cancer and an increased risk of cancer. The dietary pattern in southern China, which is characterized by more vegetables and fruits, more fish and shrimp aquatic products, regular consumption of dairy and soybean products, moderate consumption of cereals and meat and poultry, light cooking and less salt, represents the healthy dietary pattern in the east and deserves to be advocated. Following the balanced nutrition and advocating the rational diet are the key to maintaining a good intestinal microecology，preventing and controlling cancers and reducing the risk of all⁃cause mortality. This review will summarize the effects of nutrients intake and dietary patterns on human intestinal microecology as well as the incidence and prevention of cancer.