Abstract: In Dream of the Red Chamber, there are a large number of fragments of quoted poems and discussed poems, some of which are inconsistent with the original and the novel characters are inappropriate in discussing poems. Are these two special cases the defects of the novel or Cao Xueqin’s intention? Through the text analysis, it is found that Dream of the Red Chamber has deliberately changed some Tang and Song poems cited, and there are some improprieties in the poetics. Both of them are of great significance and are potentially related to the character’s identity, character and situation, making the text closer to the real life and real characters. His views on poetry originated from Yan Yu and revised Yan Yu with the poetic ideas of Tang and Song during the Ming and Qing Dynasties. His view of poetics and some “mistakes” are not only the reflection of the era atmosphere of poetics in the Tang and Song in the early Qing Dynasty, but also the needs of the characters and plots of the novel, showing the characteristics of the poetics of Dream of the Red Chambers. From these two special cases, we can see Cao Xueqin’s poetic attainments.