Objective To find out the incidence regularity and relevant risk factors of childhood (0~14 years old) asthma by investigating the prevalence in Chengdu city in 2010. Methods A total of 551 children diagnosed by asthma and 270 healthy children were recruited in this study, retrospective investigation was used by respiratory disease specialists for the survey and analysis of factors such as date of birth, the age of the first asthmatic attack, incidence and inducing factors of asthmatic attack, passive smoking, family history of asthma and other allergies, birth and feeding conditions. Results 1)Morbidity rate and seizure frequency of childhood asthma in boys were significantly higher than those in girls.2)The age of the first asthmatic attack was effected by the season of birth, that the children born in autumn had the minimum onset age, and the younger of the first asthmatic attack the higher of the asthmatic frequency of childhood asthma.3)Family history of asthma and other allergies were more common in asthmatic children compared with that in the healthy ones.Respiratory tract infection was the major cause of childhood asthma and other risk factors including passive smoking, home decoration, cesarean section and the early use of antibiotics were also revealed.4)Breast feeding after birth benefited the prevention of asthma. Conclusion The onset of childhood asthma is closely related to genetic diathesis, numerous environmental factors affect the happening, development and severity of the disease.