During the period when winter turned to spring in March 2022，an outbreak of bovine respiratory disease complex（BRDC）occurred in a beef cattle farm in Ningxia. In order to detect the pathogens，12 swabs were collected from deep nasal cavity of infected cattle to detect the nucleic acids of 10 pathogens related to BRDC，including bovine parainfluenza virus type 3（BPIV-3），bovine coronavirus（BCoV），bovine viral diarrhea virus（BVDV），infectious bovine rhinotracheitis virus（IBRV），bovine adenovirus virus type 3（BAdV-3），bovine respiratory syncytial virus（BRSV），bovine parvovirus（BPV），Pasteurella multocida（P. multocida），Mannheimia haemolytica（M. haemolytica，Mh）and Mycoplasma bovis（M. bovis）.The results showed that four pathogens were detected，specifically，both BAdV-3 and Mh were 100%，both BCoV and BVDV were 66.67%，and no other pathogens were found；for the 12 samples，mixed infection was observed，including BAdV-3+Mh，BAdV-3+Mh+BVDV，BAdV-3+Mh+BCoV and BAdV-3+Mh+BCoV+BVDV，and the mixed infection rates were 16.67%，16.67%，25.00% and 41.67% respectively. It was found that，by typing and identification for Mh and BVDV，the prevalent Mh strain fell into capsular serotype A1，and BVDV belonged to gene 1a subtype. In conclusion，the BRDC occurred in the farm was caused by mixed infection with BAdV-3，BCoV，BVDV 1a subtype and Mh A1 serotype in different combinations. Therefore，the management of biological safety and breeding should be strengthened，reasonable immune procedures should be formulated，different pathogens mixed infection should be comprehensive controlled in beef farms