Abstract：It is commonly agreed that poem theory development in Tang Dynasty is far less significant compared to the massive production of poem of the same time. Bai JuYi, however, was not only a great poet, but also developed poem theory of that time significantly. He is thus an inevitable character to study the poem theory in Tang Dynasty, and even for the overall poem development of in ancient China. Previous work, however, mainly focused on Bai's poems themselves, while largely ignored the source of his poem theory. Thus, previous study may look flourishing but are superficial indeed and are not self-sound. In this paper, we aimed to study the source of Bai's poem theory, thus to better understand his theory itself.

Keyword：Bai Juyi; Poetics thought; Book of Rites; Book of Songs;