Objective: Bronchial asthma which is abbreviated asthma is a common disease of respiratory system. According to the statistic investigation,one hundred million people suffer from asthma in the world, and there are ten millions or twenty millions asthma patients in our country. Asthma badly influences people’s health. In medicine realm, the problem related to the prevention and cure of asthma is always a focal point. Previous studies have certificated that the essence of asthma is the chronic inflammation of airway .The exact pathogenesis of asthma remains unknown. But it is believed that the most important mechanism of asthma is the disfunction of Th1/Th2. Th2 produces interleukin 4,5(IL-4, IL-5), Th1 secretes interferon-γ(IFN-γ). IFN-γcan restrain the development of Th2 as well as the immune reaction of Th2. Airway inflammation is the foundation of bronchial asthma. Oxyradical is an important inflammatory mediator in asthma. Oxyradical pathway participates in airway hyperreactivity. As a mid-product of Oxyradical,the change of MDA can reflect the level of oxyradical in vivo. Rehmannia is a frequently used traditional Chinese medicine to achieve negative acceleration and invigorate the kidney. Rehmannia is commonly used in asthma treatment. Catalpol is the most important component of rehmannia. Chinese pharmacopeia designate it as qualitating index of rehmannia. At present, the study of catalpol in adjusting and improving immune function, and resisting airway inflammation of asthma has not been reported yet. To further study the mechanism of catalpol in treating asthma and find a new way of preventing and curing asthma, asthmatic mice’s models were