Abstract: In this study, a recombinant canine serum albumin-canine interferon alpha 2(albumin-CaIFN-α2) with antiviral activity were expressed by a Bac-to-Bac baculovirus expression system. The gene HBM-Alb-CaIFN-α2, encoding canine serum albumin and the mature protein gene of canine interferon alpha 2 and linked with a honeybee signal peptide (HBM), was inserted into the pFastBac1 vector, and then transformed into DH10Bac competent cells. The shuttle plasmid rBac-HBM-Alb-CaIFN-α2 was obtained after three times of blue and white spots screening and purification, and transfected into Sf9 cell. Cytopathic changes could be observed 72 h later. Under infection with the third generation recombinant baculovirus rBac-HBM-Alb-CaIFN-α2, cells and supernatant were harvested at 3 days after infection. Indirect immunofluorescence (IFA) results showed that infected cells could show green fluorescence. Western blot analysis showed that there were about 90 kDa expression products in culture supernatant, indicating that secretory expression was consistent with the expected results. The MDCK/VSV system was used to detect the antiviral activity of recombinant Alb-CaIFN-α2,the antiviral activity was 1.70×10⁶ U·mL^-1. This study laid a foundation for further study on novel interferon products for dogs.