Abstract: Reasoning algorithm based on polychromatic sets theory for conceptual design of mechanical products is brought forward. The element and set in itself of polychromatic set theory can be described with pigmentation, so that connection between layers of Function-means tree method is described well with polychromatic sets theory. Polychromatic sets theory can act as reasoning mechanism of functions decompose and project solutions for conceptual design of mechanical products. An application example is given about the conceptual design of Machining Center.

Key words: Conceptual design, Function-means tree method, Machining center, Polychromatic sets