Abstract: In May 2017, a case of bovine respiratory disease occurred in a beef cattle farm in Inner Mongolia. In order to determine the associated etiological agents, two experiments were conducted in this study. In the first experiment, the nasal samples were collected aseptically from the diseased cattle and were inoculated onto a blood agar to isolate bacterial pathogens; furthermore, the antimicrobial sensitivity of the bacterial isolates was assessed. In the second experiment, a PCR assay was performed to screen the viral pathogens in the nasal samples from the diseased cattle. The results showed that the isolates were preliminarily identified as Streptococci and they were highly susceptible to amikacin, spectinomycin, doxycycline and azithromycin; the results of the PCR assay demonstrated that the nasal samples were positive for bovine respiratory syncytial virus （BRSV） and Mycoplasma. The combine data suggest that Streptococci, BRSV and Mycoptasma are the etiological agents responsible for the bovine respiratory disease in this beef cattle farm.