The occurrence of asthma in children is not accidental, but the result of a combination of multiple factors. One of the internal factors is difficult to change and is genetically determined. External factors are often also multi-source, and environmental factors play a contributing role. 1, genetic factors Asthma is a complex trait, multi-gene genetic predisposition of the disease. It is characterized by: ① episodic incompleteness; ② genetic heterogeneity; ③ polygenic inheritance; ④ synergistic effects. It can be reflected in many asthmatic children, for example, the majority of asthmatic children can be traced back to a history of asthma (recurrent cough, wheezing) or other allergic diseases (allergic rhinitis, atopic dermatitis) among their parents (related by blood, in the last three generations). 2.Environmental factors The most common environmental factors that trigger asthma attacks are respiratory viral infections, climate change, cold air, air pollution, dust mites, etc. Other factors include pollen, fungi, animal allergens, irritating or harmful gases in daily life, food factors, drug factors, exercise, etc. In addition, mental factors (mood changes) can also trigger asthma. 3.Prevention of different triggers To prevent asthma caused by different triggers, the most basic principle is to avoid contact with these triggers as much as possible. If parents smoke, they must quit smoking as soon as possible to prevent their children from inhaling second-hand smoke and third-hand smoke. Dust mites are a very important allergen for children. The bed, fabric sofa, cushions and curtains at home are all prone to mites. For children with dust mite allergies, the bedding should be washed and dried frequently.