The formal beauty of product design should have a relative degree of freedom. Design is done within the limitation of technology. During designing， the grasp the rule of science and technology does not prevent creation. On the contrary， it will provide free choice for creation. Therefore， the formal design of the product and formal beauty arises from it should have a relative degree of freedom.
2. Characteristics and causes of formal aesthetic in product design
Modern product design is the combination of technology and arts. A design of a product should meet consumers’ basic demands as well as their aesthetic needs. Researches on the form of product design should not be separated from aesthetics. As for the final design， the factor of beauty has already become one of the criteria used in considering whether it is good or not in modern product design. The form of product design is the external appearance of its functions. Its formal beauty is limited by its material， structure， process and other technical factors. The appearance of the product is the bearer of the external structure and also the bearer of the internal functions， all of which need to be expressed through certain materials.Different materials have different aesthetic features.