This paper uses conceptual blending theory to study the emotional poetic metaphors related to flowers in A Dream of Red Mansions. Exploration of how these emotional poetic metaphors are related to flowers in constructing meaning achieves the creative intention of the author. The proposal of this paper also reveals the "cognitive iceberg", which is hidden in the emotional poetic metaphors related to flowers in A Dream of Red Mansions so as to provide the readers with a wider range of reading horizons. Because human emotions are highly abstract, people tend to use metaphors to vividly express these abstract emotions. In A Dream of Red Mansions, the poet uses a lot of emotional poetic metaphors related to flowers to express the characters’ various inner emotions, including sadness (including loneliness, worrying, longing, hopelessness, helplessness, despair, etc.), happiness, and pride. These emotional poetic metaphors are mainly constructed by using the images of appearances, characteristics, periods, colors, fragrances, and growth environments of flowers. Through this analysis we can understand the metaphorical process, which projects from the flowers to human beings, is actually a process of conceptual blending. Through the mechanism of conceptual blending, the poet projects the flower onto human beings, using the flower to metaphorize human beings, making the abstract things more concrete while making the strange things more familiar, so as to facilitate comprehension and offer a deep impression. In addition, every poetic metaphor should be rooted in a certain cognitive model and culture model. In the process of conceptual blending of poetic metaphor, cognitive models and culture models play very important roles. The cognitive model provides certain possibilities for the formation of poetic metaphor, and the culture model is the key factor which allows these possibilities to become a reality.