Abstract: A study is conducted into the process of getting customer demands during the process of product design and development finding the way of avoiding the missing information during investigating customer demands. Based on the theory of affair-element in Extenics, a formal research is made on the front-end process of product development from user "needs", that is, the sources of the user demands. The methods of acquiring user needs and setting up the affair-element models of user needs, the importance degree analysis methods and the calculation model of user needs, the method that user need models to map into the product function models, and so on. Through a formal research of user needs and products' functions, a good solution can be derived to the problem for the product development of information on the first floor, which will contribute to the product development team in developing new products meeting user demands.

Key words: product development, affair-element, user needs, functions of products, Extenics