The invention provides host bacteria, and also provides an avian influenza universal vaccine; the avian influenza universal vaccine takes spore probiotics as a mucosal delivery vector. A CTL epitope peptide of H7N9 or other type A avian influenza virus subtypes, a cytokine IL-2 and a brevibacterium mucosal immune vaccine vector are organically combined for the first time and have complementary advantages. For the H7N9, H5N1, H5N6, H7N9, H7N2, H7N3, H7N7, H9N2, H10N7 and other type A avian influenza virus subtypes, a CTL epitope antigen is designed and screened, the spore vector is used for delivery of the antigen epitope; a spore and a spore-displayed recombinant IL-2 are used as adjuvants, and the immune type and immunoreaction level are regulated.