Abstract.Recently, the world is full of anxiety about AI(Avian Influenza). Among Avian Influenza virus subtypes, H5N1 is considered the most threatening to not only birds, but also humans as numerous human cases with high mortality have been reported. Unlike H7N9, which has not been reported infect humans, H5N8 also became infectious to humans due to dramatic mutation. As human infection cases of AI have increased, numerous researchers have been trying to develop an effective treatment against them. Thus, our project group decided to analyze the similarity and difference of H5N1, H5N8, and H7N9, since it would be useful for finding effective treatment of AI, using Decision Tree Algorithm which figures out distinctive factors of given dataset for comparing protein sequences of each viruses. The comparison using Decision Tree Algorithm, which indicates correlation among H5N1, H5N8, and H7N9, will be effective on narrowing the range of attempts on developing treatment for Avian Influenza virus.