Asthma is the most common chronic respiratory disease seriously endangering the health of children. But disease awareness and self-management skills are relatively poor in children; parents play an important role in the control of childhood asthma.To investigate the status of asthma control and severity of asthma in children and to identify impact factors.We studied 1 tertiary hospital in each of the 29 provinces. A total of 2,960 parents with children with asthma who visited those hospitals were selected for the knowledge, attitude, and practice (KAP) questionnaire survey, and separated into the controlled asthma group and uncontrolled asthma group according to children's asthma conditions in the past 12 months. Multivariate analysis was carried out based on the answers to 28 tested factors.In the past 12 months, 66.0% of children with asthma had asthma attacks, 26.8% visited an emergency room, and 16.2% were hospitalized. The total cost for asthma was significantly higher in the uncontrolled group than controlled group (χ(2) = 23.14, P.01). Twelve protective factors of asthma control were founded, such as older age of children, long disease course, high KAP scores of parents, compliance with using nasal steroids, and knowledge of "3 or more times recurrent wheezing suggesting asthma." The risk factors were eczema and family history of asthma.Children's asthma is poorly controlled. The cost of asthma is significantly higher in uncontrolled asthma than in controlled. The age of children, course of asthma, personal history of allergy, family history of asthma, parents' education level, and parents' KAP are factors that affect asthma control.