The Book of Rites (Liji in Chinese) is one of most important Confucianism classic. The book is mainly about the rites and its related aspects, including rituals, rite governing, rituals systems and rites thoughts, all of which are Li in Chinese; it is a very complicated and comprehensive concept, so it can not be translated into one English word. Most texts of the book were written by Confucius's students from the end of the Spring and Autumn Period to the end of the Warring States period. But there was a very long time throughout its being compiled into one completed book.In this thesis Feng and FengSu refer to convention and folkways created mainly by natural and geographic agents'influence, especially in traditional Chinese. There is another similar concept Su in the paper, it has almost the same meaning with the FengSu, but it has the political color compared with the FengSu. It is used to demonstrate the folk morals, convention and mostly refer to the popular living world in the thesis in ancient China governed by the emperor.The thesis is based on the reading and analysis the text meticulously to get a profound and comprehensive understanding about the Li as a whole in the book. Concretely, analyzing the related concepts of Li and Su from the different ancient classics; probing into the historical relevance and the corresponding folklore appearance about the creating reasons of Li discussed in the Book of Rites; among the historical conditions the power is the most important factor, and the cultural sprit development is another important factor; on the basis and in view of which the thesis tries to study the relationship between Li and Su, to describe their possible boundary and interplaying expression in different period; to explain some cultural presentations and problems'connotations in traditional Chinese society such as the essence culture and popular culture, upper-level culture and grass-roots levels culture and the Li's cultural meaning for modern Chinese culture.At last, from all the analysis and discussion above, I attempt to find the meaning and connection between the modern Folklore and traditional folklore history, Confucian thoughts before Qin dynasty in this aspect; to find some enlightenment to resolve some problems of our contemporary life.