In the issue of information security risk evaluation, the asset, the threat and the vulnerability are the three most important elements. Information asset identification is a primary link of information security risk evaluation process. In this paper, the decision tree algorithm was applied into the identification of information assets; the basic process of ID3 algorithm are described; the data of information system property is classified by ID3 algorithm; the decision tree was made; and the rules are extracted for providing basis of information asset recognition.