Histological structure was observed by light microscopy and expression of KGF,c-Fos and Bax was examined by immunohistochemical methods in Aguila chrysaetos lung. Results showed that the lung was consisted of bronchia and many breathing capillaries (minute trachea) around bronchia; pulmonary atrium radially disposed around tertiary bronchia; many breathing capillaries anastomosed reticulation with each other; and rich pulmonary capillaries distributed around minute trachea. KGF,c-Fos and Bax were expressed in the epithelial cells of the tertiary bronchia,pulmonary atrium and breathin capillaries,but their expression intensities were different. KGF,c-Fos and Bax may have different functions,and their cooperative expression may control the growth, development and maturity of cells in bird lung.