Objective To observe the effect of three-step sequential therapy on the pathomorphology of the bronchial lung tissues of rat asthmatic model with airway remodeling after hormone intervention using light microscope and electron microscope.Methods The airway remodeling of asthmatic rats model was induced by hormone intervention to simulate hormone withdrawal (HW)of steroid dependent asthma (SDA)patients.Altogether 150 rats randomly divided into five groups (each n =30)of airway remode-ling group,dexamethasone intervention group,pulmicort group,three-step sequential therapy group and normal control group.Morphological changes of the bronchial lung tissues of rats of all groups were ob-served under light microscope and electron microscope,and thicknesses of the bronchial walls and the bronchial smooth muscle and the number of the cell nucleus in the bronchial smooth muscle were meas-ured.Results Using HE staining,the lung tissues of rats except for those in normal control group were infiltrated by inflammation cells with different degrees,but the rats of three-step sequential therapy group were observed significantly slight inflammatory reaction.Using Masson trichromatic staining,massive col-lagen fiber in pulmonary interstitial of airway remodeling group deposited,while deposition increased dur-ing hormone withdrawal in dexamethasone intervention group,and significantly less deposition was ob-served in both three-step sequential therapy group and pulmicort group.Before HW,the thickness of the bronchial walls in three-step sequential therapy group decreased significantly compared with that in airway remodeling group(P <0.01);during and after HW,the thickness of the bronchial walls in three-step se-quential therapy group decreased compared with dexamethasone intervention group and airway remodeling group(P <0.01,P <0.05).Before HW,there is no difference (P >0.05)of bronchial smooth muscle thickness observed in all the medication groups;during and after HW,bronchial smooth muscle thickness decreased compared with dexamethasone intervention group and airway remodeling group(P <0.01,P <0.05).The number of cell nucleus in the bronchial smooth muscle of three-step sequential therapy group decreased significantly,regardless of HW,compared with dexamethasone intervention group and airway remodeling group(P <0.01).Using electron microscope,airway epithelial cilia falling off was remark-ably alleviated during HW in three-step sequential therapy group and pulmicort group,while that in dexa-methasone intervention group during or after HW was the same as the airway remodeling group. Conclusion Three-step sequential therapy could inhibit the airway remodeling by the way of relieving inflammatory changes of the bronchial lung pathomorphology of rat asthmatic model.