Abstract: Modern and contemporary studies of the Appendices to the Book of Changes (Yi Zhuan) often focused on different schools of thought implied in it. Some insisted that Appendices should be written by Confucius, some held that it was written by Daoist scholars, and some by scholars of the YinYang School. The textual analysis of Appendices may bring us a new and rational substantial understanding of Appendices. In it, those different expositions of what the Book of Changes  was and how it reflected the world mainly reflected understandings of different schools in the phase of “hundred school contention” of the whole Warring States Period, a unique traditional cultural phenomenon. The Book of Changes, based on the early Western Zhou ruling thought and culture, gradually became our nation’s rational philosophical writing instead of a mysterious divination book after Confucius’ and Daoists’ rational studies. And meanwhile, the Appendices to the Book of Changes also became a truly philosophical writing with profound ancient Chinese culture, and its basic structure of Confucius together with Daoists and scholars of changes was formed. Such an understanding may have a certain academic referential value in evaluating Confucius’ thought and historical position and reexamining ancient Chinese histories of philosophy, changeology and Confucianism.