The etiology of asthma is not well understood, and individual patient allergies and the influence of the external environment are risk factors for the development of the disease. Asthma is associated with polygenic inheritance and is influenced by both genetic and environmental factors. Many surveys have shown that the prevalence of asthma in relatives is higher than that in the population. The closer the relatives are, the higher the prevalence. The more severe the disease, the higher the prevalence in the relatives of the patient. The genes associated with asthma are not fully understood, but studies have shown the existence of genes related to airway hyperresponsiveness, IgE regulation and atopic response, which play an important role in the development of asthma. Environmental factors include certain excitatory factors: 1. various specific and non-specific inhalants such as dust mites, pollen, fungi, animal dander, sulfur dioxide, ammonia, etc.; 2. infections, such as bacteria, viruses, protozoa, parasites, etc.; food, such as fish, shrimp, crab, eggs, milk, etc.; 3. medications, such as propranolol (tretinoin), aspirin, etc.; 4. climate change, exercise, pregnancy, etc. may be stimulating factors of asthma.