In order to make clear the prevalence status of bovine viral diarrhea（BVD），infectious bovine rhinotracheitis（IBR），bovine tuberculosis（BT）and bovine paratuberculosis（BP）in scale cattle farms in Hunan Province，a serological investigation was carried out in the farms without vaccination against the above four diseases across the province by ELISA. The results showed that the positive rates of the four diseases at farm level were 51.35%，74.32%，13.64% and 22.73% respectively，and those at the individual level were 23.54%，45.45%，3.11% and 4.67% respectively. Positive antibodies against BVD and IBR were detected from the farms in 14 cities/prefectures，and antibodies against Mycobacterium bovis and Mycobacterium paratypia were detected from 4 and 7 cities/prefectures，respectively. The antibody positive rates of the above diseases were various in different scale farms，especially in larger farms where the rates were relatively high，and the multiple infection rate was 45.45%. It was concluded that BVD and IBR were widely spread and relatively serious in scale farms in Hunan Province，and BT and BP were prevalent in some areas. Besides，the above diseases were more severer in large-scale farms，and multiple infection of four kinds of diseases in different scale farms was also common. Therefore，the diseases should be further prevented and controlled due to the serious situation in the farms. In conclusion，some data obtained during the investigation was of significance for prevention and control of such diseases.