Asthma is a common obstructive airway disease and the prevalence rate has increased in many countries, including Taiwan. The effects of swimming are not only good for body but also stimulate skin and nervous. Because the environment is warm and humid during exercise, the stimulation is less for airway. Most studies showed that swimming exercise is helpful for asthma. The author’s study was to investigate the effects of a 6-week swimming intervention for children with asthma on pulmonary function testing and the severity of asthma. Results showed that a swimming program could improve pulmonary function parameters and reduce the severity of the asthma attack for asthmatic children.