Abstract: The study used pathology methods to observe and research the five natural doubtful respiratory syndrome cases. The results showed that: the lungs was paleness, Most of the cases were hard cases. Under the microscope, the lungs Consolidation mainly represent alveolar wall and interstitial substance widened, bronchial wall thickened, macrophagocyte accumulation and proliferation, but mechanocyte increased in non-dominant. The microscopic pathological information in this study contributed to porcine respiratory disease syndrome clinic diagnosis. 

Key words: porcine respiratory syndrome; lungs consolidation; microscope