To analyze the biological characteristics of Pasteurella multocida in bovine respiratory tract and its prevalence in large-scale cattle farms,bacterial isolation,culture,and morphological observation were conducted on the lungs and liver samples of dead cows suffering from respiratory diseases in Hohhot,Inner Mongolia.The isolated strains were studied through biochemical testing,16S rRNA gene sequencing,specific primer PCR identification,capsule serotyping,pathogenicity testing,virulence gene testing,drug sensitivity testing,and drug resistance gene detection methods.The results showed that six strains of Pasteurella multocida serotype A were isolated and identi-fied from the lungs of diseased and dead cows.After sequencing the 16S rRNA sequence of the bac-teria,it was found that the six strains of Pasteurella multocida had the closest genetic relationship with the Chongqing isolate CQ2(CP033599.1).The results of mouse pathogenicity test and viru-lence gene detection showed that all isolates were pathogenic and carried at least 16 or more related virulence genes such as exbB,nanB,sodC,oma 87,etc.,but no hsf1 and toxA were detected.The results of drug sensitivity tests and resistance gene detection showed that the isolated strains were sensitive to different degrees of antibiotics such as ciprofloxacin,ofloxacin,and cefotaxime.They were resistant to streptomycin,clindamycin,and lincomycin,and resistance genes of str A,strB,and tet(H)were detected.The results indicate that there is a certain correlation between the pathoge-nicity and virulence genes,drug resistance phenotype,and drug resistance genes of Pasteurellamultocida type A in cattle.It is recommended to use quinolones(such as ciprofloxacin)and cepha-losporins(such as cefotaxime)antibacterial drugs in clinical practice,which can provide scientific basis and prevention and control plans for the prevention and treatment of respiratory diseases caused by Pasteurella multocida in cattle farms,and lay a foundation for the epidemiological mo-nitoring of bovine respiratory multocida pasteurellosis.