Abstract: It is a new academic attempt to analyze the construction process of Lao Zi's concept of "Dao" from the perspective of cognitive metaphor. Lao Zi called “Dao” is so “big” that it's unlike anything, denying the similarity between “Dao” and the world of experience, which is to say that Dao can neither be described by experience nor comparable in substance. However, the fact maybe just the opposite. The conceptual metaphor on human experience is inevitable in conceptualizing the metaphysical “Dao”. Ontological metaphor, one of the most important and fundamental in all conceptual metaphors, plays an important role in the understanding and definition of metaphysical concepts. In conceptualizing the metaphysical “Dao”, ontological metaphor is not a choice but a must and human experience on the entity is neither avoidable nor deniable in Lao Zi' metaphorical thinking.

Key words: Dao, Ontological metaphor, Conceptual metaphor