The Rectification of Mao's Poetry by Kong Yingda et al is both a summary of the studies since Han and Wei dynasties, and a masterpiece in the like field in Tang dynasty, thus influencing the oncoming researches on the Book of Songs. This paper focuses on the three poetic lessons, melodious psalmody and his insightful reinterpretation of the six rituals are considered as most valuable in the work. As a compulsory textbook for the imperial examination, it combines various political concepts of contemporaries, and exerts great influences upon poetic creativity.