From an integrated cognitive-functional perspective, this study establishes yu as a superordinate theoretical category encompassing metaphor, metonymy, and grammatical metaphor. It constructs a cognitive-functional framework of experiential meaning to systematically explore three core issues: the nature, origin, and function of yu. The study defines yu as a “conceptual-rhetorical complex” and establishes a unified categorical system based on the three-dimensional parameters of similarity, contiguity, and reconstrual. The study demonstrates that yu originates from the embodied interaction between humans and the world, and develops into a dynamic resource system through the bidirectional processes of experiential conceptualization and experiential socialization. This resource system plays a central metafunctional role in conceptual construction, interpersonal negotiation, and textual organization.