The invention discloses an avian 
Pasteurella multocida 
gene knockout strain mediated by Ngpiwi 
protein and a construction method and application thereof. The avian 
Pasteurella multocida 
gene knockoutstrain is a deleted strain which deletes an ORF sequence or a partial sequence of a latent 
virulence-
related gene on the avian 
Pasteurella multocida 
genome. Firstly, that recombinant 
plasmid with Ngpiwi and the left and right homologous arm of the 
target gene sequence to be deleted is successfully construct; secondly, the recombinant 
plasmid was electroporated into Pasteurella multocida and induced to double-exchange recombination at 28 DEG C, the strains deleted the 
target gene sequence were screened by PCR, and then the 
plasmid was induced to lose at 42 DEG C, thus the strains deleted the potential 
virulence gene sequence were obtained. The genetic 
operating system has the advantages of small plasmid, easy operation, wide application, no potential miss-targeting effect, high knockout efficiency and no resistance 
gene screening marker, which provides an excellent tool for the development of 
genetic engineering vaccine of avian Pasteurella multocida.