A small number of people who ingest or come into contact with certain foods cause strong reactions, most of which are due to an abnormal immune response, called food allergy. Food allergy is a common chronic allergic disease, which is prone to recurrence and life-threatening in severe cases. The prevalence of FA varies among different regions and populations. Foreign data show that the prevalence in children in the United States is 6-8% and in the total population is 3.5-4%; in France, the prevalence in school students is 4.7%. For example, the incidence of peanut allergy in the United Kingdom and the United States has increased 1-fold in the past five years. Local surveys in China show that the prevalence of FA among young children within 2 years of age in Chongqing is 5.2%; the prevalence among school students in Shenyang is 6% in the 15-24 age group. Food allergens in children or adults have different characteristics: common food allergens in children are: eggs, milk, peanuts, wheat, fish, shrimp and crab, while in adults, it is mainly fish, shrimp, crab, peanuts and nuts. In addition, the types of allergenic foods vary significantly from region to region. In addition to egg and milk, peanut allergy is most prevalent in the United States and the United Kingdom, while in the Middle East it is sesame and in Japan it is wheat. In both children and adults, food allergy can induce the following symptoms: itching, tingling or swelling of the mouth, lips or throat; rash, skin redness, swelling and itching; diarrhea or vomiting; runny or stuffy nose, red, sore or watery eyes; difficulty swallowing; coughing, wheezing, difficulty breathing, stiff joints, fainting and shock. Children with food allergies often develop atopic dermatitis, asthma, allergic rhinitis, urticaria and other allergic diseases at different ages of their growth. Studies have shown that active prevention and treatment of food allergy can help to cut off the “allergic process” disease chain and reduce the occurrence of allergic diseases. Food allergy is mainly manifested as an adverse reaction mediated by the immune mechanism after eating, which can involve the digestive tract, skin, respiratory tract, circulatory system, etc. Severe allergy can lead to multiple organ system involvement, respiratory distress, anaphylaxis, etc. In recent years, severe food allergy is on the rise in clinical practice. At present, the main basis of food allergy diagnosis includes the following: 1. A detailed medical history is important for the diagnosis of food allergy. When taking the history, attention should be paid to the causal relationship between the food and the appearance of symptoms. Generally speaking, IgE-mediated food allergy has a short latency period and it is easy to find allergic foods. However, to find the true allergen from certain mixed foods, it often relies on more auxiliary tests. 2. Skin test: For food allergy, puncture test should be especially advocated. Compared with intradermal test, puncture test has better sensitivity, specificity, repeatability and safety, and for some allergens (especially fruits and vegetables) freshly squeezed juice can be used instead of allergen dip for puncture. If the patient is highly allergic to a certain food (such as asthma, laryngeal edema, syncope or shock after eating), the skin test may not be done, and the in vitro test may be performed directly. 3, in vitro test: according to the medical history, symptoms, signs and skin test results of the prompt, choose the specific IgE test items. The results of the specific IgE test should be given a reasonable explanation. 4. Food diary and recipe diagnosis: The food diary can be considered as a supplement to the clinical history, requiring the patient to keep detailed records of the types of food eaten at three meals a day as well as the presence or absence, nature and degree of symptoms, with a view to discovering some patterns. 5. Food stimulation test: It can be divided into single-blind, double-blind stimulation test and placebo-controlled stimulation test. It is usually considered that the double-blind placebo-controlled excitation test is the gold standard for the diagnosis of food allergy. However, because of the great risk to both the doctor and the patient, and the high conditions required for the implementation of the food excitation test, food excitation test is rarely done in the clinic. Due to the high risk of food provocation testing and the limitations of many conditions, the diagnosis of food allergy is based on detailed history and symptoms, intradermal testing, skin prick, and specific IgE testing to determine whether food allergy is present.