There is no clear-cut which nutrient or food can improve the immunity of lung cancer patients, and it is recommended to follow the recommendations of dietary guidelines for rational diet. According to the recommendations of relevant dietary guidelines for patients with malignant tumors, lung cancer patients can adopt the following dietary behaviors in order to improve immunity: 1. If patients have more serious nutritional depletion, patients need to ensure the daily intake of 1.2~2g/kg of protein, and protein needs to be poultry, meat, eggs and milk. 2. Intake of fat, carbohydrates: lipids need to eat more food rich in n-3 and n-9 fatty acids, such as daily life common flaxseed oil, olive oil, etc., and the best daily intake of carbohydrates 200g ~ 400g of coarse and fine with cereals. 3. Ensure adequate water intake to 1500~1700mL. For all kinds of nutritional products and health care products, it is recommended that cancer patients take them with caution, for one thing, some nutritional products are mixed with all kinds of additives that will affect the therapeutic efficacy of the treatment, and for another, some nutritional products consume a large amount of economic costs and their nutritional value is almost unable to catch up with the benefits of a reasonable diet.