It investigates the application of Affordance concept in product design from the perspective of cognitive theory. By describing the origins of Affordance theory in the field of cognitive and development in the field of design， it introduced Naoto Fukasawa proposed "unconscious design" concept，then researched the role of Affordance in user， product，environmental. It summarized four Affordance types in product design，and analyzed that how Affordance worked in the product design in detail by investigating the cases of the existing excellent products. Finally， it put forward that designers should grasp four directions to design better quality product from the impact of the Affordance of the products.