In this paper, the identification theory based on characteristics of the inner pages is presented for the first time. This theory cannot be ignored in the identification of Naxi manuscripts. The identification theory based on characteristics on the inner pages is divided into identification based on inner page format, identification based on illustrations, identification based on frame and identification based on initials and separators. The rationality of identification theory based on characteristics on the inner pages is confirmed through demonstrations. At last, principles, rules and limitations of identification based on characteristics on the inner pages are summarized. The advantage of this theory is simple and effective, and the disadvantage is too dependent on scriptures inside pages of the style and color.