In this paper, the histopathological structure of digestive system, spleen and lymph node in an elk (Elaphurus davidianus) infected by bovine viral diarrhoea-mucosal disease (BVD-MD) was observed by routine paraffin section and H.E staining. The results show that the lesions mainly exist in the layer of mucosa: cells of epithelium desquamated, necrosis, capillaries in lamina propria hyperemia, and inflammatory cells penetration. Lesions in spleen are mainly acute septicemia, with severe hyperemia and haemorrhage in red pulp, and disappearance of white pulp. The necrosis in lymph node is severe, with destruction of its histological structure, and only appearance of lymph cells penetrated. The histopathological observation has provided morphological data for clinical diagnosis.