Abstract: Most childhood asthma is easily controlled with regular use of inhaled corticosteroid (ICS)and rescue bronchodilators.However,despite effective therapies,there are many children with severe asthma who do not achieve well control.Those proportion of children will have persisting symptoms,frequent exacerbations and frequent hospitalization/emergency department visits.The reasons are complex and diverse.Although treatment compliance is a very important factor,about 70% of the variability is determined by genes.Many gene polymorphisms have been identified to be associated with asthma,such as susceptibility,airflow obstructuin,airways responsiveness and treatment response.To improve the treatment and the quality of life,and achieve the individualized targeted therapy matched with the severity of disease,it is important to identify the relationship between gene polymorphism and the severity of children asthma.