The logo design mainly represents the visual design, it is the same with other kinds of design in thinking, principle, and way. Whether in the logo design or others, all designers should observe a common design principle, it is that all the design material symbols should have the common, which is the basic difference between design and art. In this paper, the authors expatiate the meanings and methods to define the symbols of subject material in logo design, which is also useful to other kind of art designs.