This classification is divided into 7 levels, basically divided into 5 levels, as common sense. All central colleges, comprehensive branches, professional libraries and subject reference rooms can use this classification level method to classify books. The first level is divided into humanities books and nature books according to the attributes of the universe. The second level is divided according to the basic subject attributes of books. Basic humanities subjects: philosophy A, religion B, ethics C, logic D, aesthetics E, psychology F, language G, literature H, art I, politics J, economy K, military L, law M, education N, sports O, media P, information Q, management R, business S, history T, archaeology U, nationality V, life W, wealth X. J electric power, K textile, L food, M building, N mine, O metallurgy, P energy, Q transportation, R aerospace, S medicine, T project, U agriculture, V forestry, W aquaculture, X computer. The third level is divided according to the standards of books affiliated disciplines. The fourth level is divided by the functional attributes of books (writing, learning, teaching and helping). The fifth level is divided into works (works, theoretical works and applied works), academics (annotation, evaluation, contention, discussion, research, textual research and translation), teaching (school textbooks, social training textbooks, self-study textbooks, reference materials, handouts, learning materials, popular reading materials, experimental exercises, test questions and exercises, teaching syllabus) and help (teaching syllabus) according to the category attributes of books. The sixth level is divided into domestic and foreign original books (non-disciplinary definition space) according to the international space of books. The seventh level is divided into book time series (non-disciplinary time series).