Abstract: Ovine pulmonary adenomatosis（OPA） and ovine progressive pneumonia（OPP）are two kinds of incidental respiratory system diseases for the improved sheep.Both of them can cause obvious pulmonary lesions.In order to identify two kinds of diseases from the histopathological changes,macroscopical lesions of OPA and OPP natural cases in lung were analyzed.The lung of OPA and OPP dead sheep was collected to make into paraffin sections.After HE staining,the results were observed by optical microscope and pictures were taken.And the pathomorphological changes were recorded.