Abstract: From the Han Dynasty, Daoist of Elixir introduced Zhouyi to combine it with Huang-Lao thought and the practice of making an elixir, thus forming a unique set of sign systems. Qian and Kun especially became the outline of the metaphor in the development of the Golden Elixir practice. Kun has close metaphor correspondence to cultivate oneself to establish the foundation in elixir practice while Qian refers to the four-step progress: practicing essence（精）to form pneuma（气）, practicing qi to form spirit（神）, practicing spirit（神）to return to xu（虛）and practicing xu（虛）to reach Tao. Based on this, we can see clearly the application of Zhouyi in inner elixir practice and the essence of the inner elixir.

Key words: Zhouyi, Inner elixir, Peng, Dragon, Mysterious Yellow（玄黃）