For breast cancer patients, diet is an essential part of the prevention, treatment and recovery process. A reasonable diet for breast cancer patients can improve the body’s resistance, which is very beneficial to the treatment and recovery of patients. The dietary characteristics of breast cancer patients at different stages are different. (1) High-calorie and high-carbohydrate diet can supply breast cancer patients with enough calories, reduce protein consumption and prevent hypoglycemia; it can protect liver cells from damage by anesthetics; it can also increase body resistance to make up for the calorie consumption caused by insufficient food after surgery. (2) Breast cancer patients need to take in enough protein. Lack of protein in the diet will lead to malnutrition edema, which is not conducive to postoperative wound healing and recovery of breast cancer patients. A high-protein diet can alleviate excessive protein consumption caused by certain diseases, reduce postoperative complications of breast cancer, and enable breast cancer patients to recover as soon as possible. (3) A high vitamin diet is needed. Vitamin a can promote tissue regeneration and accelerate wound healing. Vitamin k is mainly involved in the coagulation process, which can reduce intraoperative and postoperative bleeding. b vitamin deficiency can cause metabolic disorders, and wound healing and tolerance are affected. Vitamin c can reduce capillary permeability, decrease bleeding, and promote tissue regeneration and wound healing. Therefore, breast cancer patients must eat more fresh vegetables and fruits rich in vitamins before surgery, and some patients may also need to supplement vitamin tablets according to the doctor’s recommendation. Post-operative diet for breast cancer patients: (1) Supply protein foods that can be easily digested and absorbed, such as milk, eggs, fish, soy products, etc., which can improve the body’s anti-tumor ability. (2) Eat appropriate amount of sugar to supplement calories. It is better to supplement glucose, and it is also advisable to eat more sugar-rich foods such as honey, rice, noodles and potatoes to supplement heat. (3) Eat more foods with anti-tumor effect, such as turtle, mushroom, black fungus, garlic, seaweed, mustard and royal jelly, etc. (4) Vitamin a and vitamin c have the effect of stopping cell malignancy and proliferation and increasing the stability of epithelial cells. Vitamin c can also reduce the general symptoms of radiation damage and verify the rise of white blood cell level; vitamin e can promote cell division and delay cell aging. Vitamin b1 can promote patients’ appetite and reduce the symptoms caused by radiation therapy. Therefore, more foods rich in the above vitamins should be eaten, such as fresh vegetables and fruits, sesame oil, cereals, beans and animal offal. (5) For patients with radiotherapy and chemotherapy, it is generally advisable to eat cool food and cold drinks; for patients with cold sensation, it is advisable to eat hot food. (6) Diversify the diet, pay attention to the color, aroma, taste and shape of food, promote the appetite of patients, cook food by steaming, boiling and stewing, avoid food that is difficult to digest and forbid drinking alcohol. (7) For those who have difficulty in chewing, swallowing, digestion and absorption and lack of special nutrients after tumor surgery in various parts, different diets and supplements of the lacking nutrients can be given according to the situation, and if necessary, a diet of nutritional elements can be given to enhance patients’ resistance. After breast cancer chemotherapy, some new foods can be chosen to promote appetite, for example, patients who often eat pork-based foods can be replaced with eating fish, lamb and chicken. Changing the cooking method can make the food have different color and flavor, which can increase the patient’s appetite. No matter what kind of food is cooked, it must be cooked to the degree that the food is well cooked, so that it can be easily digested and absorbed by patients. Breast cancer patients should eat more fresh vegetables and fruits with high vitamin content, and eat some light and refreshing raw cold dishes and fruits, especially during chemotherapy and radiotherapy, which have obvious appetizing effects. In the process of radiotherapy, breast cancer patients may have adverse digestive reactions, such as nausea, loss of taste, loss of appetite, which may affect the amount of food eaten, resulting in nutritional deficiency and reduced resistance, which is not conducive to normal tissue repair. Avoid eating foods that are too cold, too hot, greasy, spicy and other stimulating foods. It is better to eat slowly so that food can be fully chewed to facilitate digestion and absorption, and to prevent abdominal pain and distension caused by rapid eating. The dietary principles for breast cancer patients are as follows: (1) Be flexible with the treatment. Breast cancer patients need to make efforts to eat and supplement nutrition before and after surgery. During the radiotherapy period, the diet should be light and palatable, and should not include more thick and greasy food. (2) Reasonable arrangement and smart cooking. After the completion of the treatment plan, it is necessary for breast cancer patients to eat foods that are beneficial to the prevention and treatment of breast cancer. The patients should eat more seafood, such as seaweed, kelp, jellyfish, sea cucumber, mussels and oysters; beans, such as mung beans, red beans and mung bean sprouts; vegetables, such as taro, wild rice, water chestnuts, winter melon, mushrooms, monkey mushrooms, shiitake mushrooms and tomatoes; fruits, such as oranges, apples, hawthorn and fresh kiwi; other foods, such as snapper, black fish, barley and wood ear. (3) White ginseng or American ginseng can also be taken during the treatment period, and after the treatment is over, ginseng can still be taken in the winter season. (4) Diet should be moderate and not excessive. Excessive nutrition and obesity will have a negative impact on the treatment of breast cancer. In the long-term life after treatment, breast cancer patients should adhere to the principle of diet in moderation but not in excess, while ensuring nutritional needs. The total daily intake of calories, fats and sugars should be balanced, and overeating should be avoided. In conclusion, whether in daily life or before and after breast cancer examination or treatment, it is necessary to pay attention to reasonable dietary habits for breast cancer treatment and prevention of breast cancer. A healthy life is the only way to make a healthier life.