Abstract: A model establishment of pulmonary fibrosis was causead by a single intratracheal injection 0.1mg pingyangmycinum in mice. The effect of tetrandrin, a herbal powder, 50mg/kg/time, on the pathological development of pulmonary fibrosis, and the activity of superoxide dismutase （SOD）, angiotensin converting enzyme （ACE）, quantity of hydroxyproline （IIYP） in this mice model were investigated. We also contrast tetrandrin with cortisol which is the traditional "antifibrosis agent. The result showed that tetrandrin may inhibit formation and development of pulmonary fibrosis in defference degree. On the other hand, tetrandrin and cortisol all may increase the activity of SOD of lung tissue and reduce the quantity of HYP of lung tissue, decrease the activity of serum ACE in mice. We also discussed the possible mechanism of tetrandrin in this paper.