Abstract: Abstract： As an authoritative book of the studies of The Book of Songs in the Song Dynasty, Commentary on the Classic of Poetry is full of reform spirit. On the one hand, the critical method changes from the "viewingworld" to the "viewinglaw"; and on the other hand, the commentary on the content unfolds the "imperfection" instead of the "purity". What's more, the orientation of application or the method of interpretation is no longer the "allegorical" or the "abstruseness" but the "stirred" or the "easiness". The main causes of this reformation are as follows: having a brannew learning thinking; possessing a literary insight; and emphasizing a perceptive, textual method.

Key words: Zhu Xi, Commentary on the Classic of Poetry, reform spirit, cause of formation, Key words： studies of The Book of Songs in the Song Dynasty