To solve the problems of the index's fuzziness and the corresponding weight's incompleteness in the evaluation of various schemes of mechanical products in an environmentally oriented design, a synthetical study method of the relative green degree based on the fuzzy AHP-TOPSIS is developed to improve the related solutions. The advantages of the fuzzy AHP and the fuzzy TOPSIS are well combined. Firstly the fuzzy AHP is applied to divide the indexes into an orderly hierarchy to determine the weight of each hierarchy level. Then the fuzzy AHP-TOPSIS is established combined with the fuzzy AHP to determine the optimal scheme according to the degree of closeness between certain qualitative and quantitative indices of benefit and of cost and the ideal solution. Both the quantitative and qualitative indices of benefit and of cost are distinguished strictly, and the principle and the systems of index evaluation of mechanical products by environmentally oriented design are established based on the full life circle. The case analysis shows that it is reasonable in theory and functional in practice, as a result, it is effective and feasible.

AHP  /  fuzzy AHP-TOPSIS  /  environmentally conscious mechanical design  /  green design  /  green degree