Abstract: Diagnosis of bronchial asthma mainly depends on history of disease and pulmonary function examination, but patients with contraindications and poor cooperation are easy to be misdiagnosed and missed diagnosed. Using electronic nose detection technology to detect exhaled volatile organic compounds in patients with bronchial asthma is an economic, rapid and high diagnostic method with higher diagnostic rate method for early and rapid screening of bronchial asthma, and assessment on the efficacy of steroid treatment and prediction of steroid response.