Many post-operative patients and family members of gastrointestinal tumors ask the same question: Is there any “contraindication” after surgery? This question should be answered in different stages. For patients with gastrointestinal tract surgery, if they cannot eat normally at the early stage after surgery, intravenous rehydration should be the mainstay, and the postoperative diet should start with thin and soft, and then increase other diets after the body gradually adapts. On the whole, we should pay attention to chewing slowly, food should be easy to digest, and minimize the consumption of foods that can cause gastrointestinal distention (such as sucrose, milk, soy milk, etc.). In general, there are some foods and habits that should be avoided by patients after gastrointestinal surgery, such as: (1) Avoid smoking and alcohol. (2) Avoid spicy and stimulating foods, such as onion, garlic, ginger, pepper, chili, cinnamon, etc. (3) avoid mold, pollution, hard, rough, multi-fiber, greasy, sticky and indigestible food. (4) Avoid frying, deep-frying, smoked, pickled, raw food. (5) Avoid overeating, hardening and stuffing. The recovery diet after gastrectomy is very important, both to make up for the chronic consumption of preoperative disease and to fill the loss of surgical trauma. Therefore, less food and more meals should be used for a longer period of time, i.e., increase the number of meals and reduce the amount of food eaten each time. At the same time, we should try to select foods with sufficient nutrition, high protein, high vitamin and sufficient vitamin A, B and C content to promote the repair of trauma. Such as eggs, dairy and its products, lean meat, soy products such as tofu and soy milk, fresh vegetables and ripe fruits, etc. Avoid stimulating and indigestible foods, such as chili, celery, wine, coffee, strong tea and celery and leek which contain much crude fiber. Patients with colorectal cancer should pay attention to the intake of fat after surgery. High-fat diet will promote the occurrence of intestinal tumors, especially polyunsaturated fatty acids, which can lower blood lipids but have the effect of promoting cancer. Cholesterol itself is not carcinogenic, but reacts with gallstone acid at the same time and has a pro-carcinogenic effect, indicating that gallstone acid is a pro-carcinogenic factor. Therefore, patients with colon cancer should not eat too much fat, with total fat accounting for less than 30% of total caloric energy, and the ratio of animal and vegetable oils should be appropriate. Dietary fiber-rich vegetables, such as celery, leek, cabbage, radish and other green leafy vegetables, can stimulate intestinal peristalsis, soften stool, increase the number of bowel movements, and take away carcinogenic and toxic substances from stool. In conclusion, postoperative patients with gastrointestinal tumor need to pay attention to their diet so that they can recover better.