The invention aims to provide a bacillus licheniformis and application thereof. The preservation number of a bacterial strain of the bacillus (Bacillus lincheniformis) LV005 is CCTCC M 2013262. The bacillus licheniformis LV005 disclosed by the invention is screened from an alimentary canal of a prawn, and has the advantages of improving the composition and the number of dominant microbial populations in the alimentary canal of the prawn, forming and maintaining good microecological balance of the alimentary canal, and resisting the adhesion and the proliferation of viruses in the alimentary canal through nutrition competition, space competition, bacteriocin secretion and the like. The bacterial strain can activate the expression of prophenoloxidase, superoxide dismutase, lysozyme, heat shock protein, lipopolysaccharide-glucan conjugated protein, signal transduction, transcriptional activation factors and the like of the prawn with relevant pathogenic infection resistant molecules, and retard the proliferation rate of the viruses in the body of the prawn, so that the bacterial strain has various biological functions of improving the activity of the protease, the lipase and the amylase of the prawn, promoting the digestion capacity of the prawn and the digestion for feed nutrients, improving the stress response resistant capacity of the prawn and the like.