A approach based on Analytic Network Process (ANP) and fuzzy theory is proposed in order to improve the evaluation system, which is comprised of correlative indexes, of product conceptual design schemes, as well as to select the best scheme and guide the continuous improvement of it. With the application of the concept of fuzzy measure, a new algorithm with ANP is introduced to replace Shapley algorithm to get the fuzzy measures. The interaction values among arbitrary number of evaluation indexes are calculated by plugging the fuzzy measures into the interaction index formula, which is deduced from Shapley value formula and fuzzy reasoning. Then according to the interaction values, the best scheme selected by calculating Choquet integral is improved further. Finally a case study of aged mobile phone design evaluation is conducted to demonstrate the application of this method.