Objective To investigate and discuss the prevalence and the relevant risk factors of bronchial asthma in Shenzhen city China. Methods We used standard scheme and questionnaire, and performed stratified-cluster-disproportional-random-sampling survey for the population of five communities. Results A total of 6 248 people were surveyed. 50.5% (3 156 of 6 248) of whom were men and 49.5% (3 092 of 6 248) were women. In this survey, forty asthma patients were found, and the overall prevalence rate was 0.64%, three groups with higher prevalence were 66 to 75 years (54‰), 56 to 65 years (23‰) and 14 to 17 years (12‰) respectively. Risk factors found that among 40 asthma patients, people often exposed to secondhand smoking were reported by 40% and children exposed to their father’s smoking from fetus were reported by 57%. People with asthma with allergic rhinitis were reported by 50%. The attacks were caused by common cold and changing temperature or inhaling cold air were 45% and 30% respectively. About 86% of children suffered from asthma before 2 years old. Conclusion This survey has basically reflected the distribution, frequency and intensity of asthma. The overall prevalence rate is 0.64% from which it would be estimated that there could be 25 900 asthma patients in Shenzhen city, the relavent data will provide basis for the future research, mass prevention and the treatment of asthma.