Abstract: [Objective] To understand the epidemic situation of bovine respiratory disease in a dairy farm in Kaili City. [Methods ] Bovine respiratory syncytial virus （BRSV）,bovine viral diarrhea （BVDV）,infectious bovine rhinotracheitis（IBRV） and bovine mycoplasma infection were detected in 142 serum samples by Elisa.[Results ] BRSV,BVDV,IBRV and Mycoplasma were common pathogens in a dairy farm in Kaili City. The positive rates of BRSV,BVDV, IBRV and Mycoplasma were 41.5%（59/142）,40.1% （57/142）,45.0%（64/142）and 33.8% （48/142）respectively. The single infection rate of four respiratory diseases in calves was 15.1% ~ 45.5%, BVDV infection was the most serious（45.5%）,and the single infection rate of adult calves was 33.8%~45.1% . In addition,there were mixed infection of IBRV,BRSV,BVDV and Mycoplasma in dairy farm,the double infection rate was 18.3%~30.2% ,BVDV + IBRV infection rate was the highest （30.2%）,BVDV + Mycoplasma + IBRV infection rate was the highest,19.7%. The rate of quadruple infection was 9.9%. [Conclusion]There are four kinds of diseases in A Dairy Farm of Kaili City,and the pathogens are infected to different degrees. The epidemic control of the pathogens should be strengthened and the management level of the dairy farm should be improved,to reduce the incidence of disease and economic losses in dairy farms.

Key words: bovine respiratory disease, serology, investigation, ELISA detection, multiple infection